Sky News’ Data and Forensics team has spoken to four experts to answer the question – how does a pager or hand-held radio explode?
The pagers that exploded in Lebanon on Tuesday are consistent with the AR-924 model of pager with Gold Apollo branding.
The Taiwan-based company has distanced itself from the devices, saying they were made under licence in Budapest by a firm called BAC Consulting.
The chief executive of BAC Consulting, Cristiana Barsony-Arcidiacono, told NBC News, Sky News’ US partner: “I don’t make the pagers. I am just the intermediate. I think you got it wrong.”
Meanwhile, Icom, the Japanese maker of the brand of walkie-talkies linked to the deadly blasts, has said it stopped making the model a decade ago and it would be impossible to lace them with explosives during manufacturing.
So while it might not be clear at what stage the pagers or radios could have been turned into bombs, experts can say how it might have been done.
Image: The remains of what is said to be one of the exploding pagers
First, let’s look at the explosive – you only need a very small amount, a gram or two is enough to “explode someone’s arm or face”, says Dr Eyal Pinko, a former Israeli navy and intelligence operative.
It is not yet clear exactly what type of explosive was used. There have been unverified reports pentaerythritol tetranitrate, or PETN, was used. Experts told Sky News it also could have been TNT or another equivalent.
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“The point is that you can mix them in with another component effectively to make a plastic explosive,” Andrea Sella, professor of chemistry at University College London, says. 
“So that means that you could conceivably insert some of this stuff into the nooks and crannies [of a pager].”
The explosives could have been in the battery, inside a detonating device or hidden elsewhere in the pager, Dr Pinko says. 
But once the explosives are in the pager, how can it be remotely detonated?
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1:07
Lebanon explosions: What happened?
The other thing that will likely have been added to the pager is a detonator, says Carl Robson, who used to be a British army bomb disposal operator and is now a bomb disposal project manager for Igne UXO. 
A detonator is a “small cylindrical barrel” which, even without any added explosives, would easily cause injury once initiated, Mr Robson says. 
To initiate the detonator, you need a power source. In this case, that is the battery for the pager 
But how does the battery set off the detonator?
You need a trigger – Mr Robson compares it to a light switch, and in this case, the flick of a switch is a particular message being sent to the pager. 
This message, which could have been a specific string of letters or symbols, is identified and “starts creating the explosive chain”, Dr Pinko explains.
“Which means that it takes a current from the battery, heating the explosive to the level of energy which is needed. And then [the explosion] occurs. 
“You only need a fraction of a second [of heating] to get this kind of explosion,” he adds.  
Sean Moorhouse, a former British Army officer and explosive ordnance disposal expert, puts it another way: “Normally the pager beeps when you [get a message]. What they’ve done is they said, ‘OK, instead of beeping, send the charge that normally goes to the beeper to the detonator instead’.”
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1:07
Lebanon explosions: What happened?
But he says there’s still a question mark over how the pager was programmed to react to the message. 
The second wave of explosions killed 20 people, while 12 people died and almost 3,000 more were injured when the pagers exploded.
Mr Robson says the higher death rate could have been down to the nature of the communication devices – hand-held radios are more likely to be used in crowded places, while pagers are carried at all times.
The Data and Forensics team is a multi-skilled unit dedicated to providing transparent journalism from Sky News. We gather, analyse and visualise data to tell data-driven stories. We combine traditional reporting skills with advanced analysis of satellite images, social media and other open source information. Through multimedia storytelling we aim to better explain the world while also showing how our journalism is done.
The Palestine Red Crescent Society (PRCS) has demanded an independent investigation into the “atrocious” deaths of 15 aid workers killed by Israeli troops in Gaza in March.
The group’s president, Dr Younis al Khatib, said he had asked the UN Security Council to form an investigation committee into the “intentional killing of the medics”.
In response to Sky’s Alistair Bunkall, spokesman David Mencer claimed the killings were the result of Hamas hiding among civilians and using them as human shields.
But speaking in Ramallah, Dr al Khatib said those responsible must be held “accountable for these crimes” via international humanitarian law and the Geneva Convention.
“It’s not enough to comfort us with condolences and nice words of investigation and accountability. There has to be action taken,” he added.
He urged an “independent and thorough investigation of this atrocious crime” and that “no one should be above the law”.
“So many questions being asked of the Israelis,” he said.
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“Why were they killed? Why did you destroy the ambulances after killing them? Why did you try to dig deep and hide the ambulances? They have to answer for that.”
The Israel Defence Forces (IDF) said on Monday that a preliminary inquiry into the shooting “indicated the troops opened fire due to a perceived threat following a previous encounter in the area”.
The IDF added that “six of the individuals killed in the incident were identified as Hamas terrorists”.
It comes after footage at the weekend showed the moment the aid workers were killed, with ambulances and fire insignia clearly visible and red lights flashing.
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Phone footage contradicts Israeli claims of killing of Gaza medics
The paramedic filming, later found with a bullet in his head, is heard saying there are Israelis present and reciting a declaration of faith often used before someone dies.
He adds: “Forgive me, mother, this is the path I chose mother, to help people, forgive me, mother, I swear I chose this path only to help people.”
The Israeli military originally claimed the vehicles – which were travelling north of Rafah on 23 March – didn’t have headlights or emergency signals on and were targeted as they looked “suspicious”.
An IDF investigation is ongoing, but an Israeli government spokesman claimed on Monday that “six Hamas terrorists” were among those killed.
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1:52
‘Demands’ for medic death investigation
Still many unanswered questions
It’s now more than two weeks since 15 medics were shot dead by Israeli forces in southern Gaza and there are still many unanswered questions.
Israel initially said that the medics had been fired upon because they were behaving suspiciously and travelling without lights on.
When footage emerged at the weekend contradicting that, and showing that the vehicles were clearly marked as ambulances, the IDF released a new statement admitting that their soldiers made a mistake.
For the first time since that video was made public, Sky News was able to put a series of questions to Israeli government spokesman David Mencer about the incident.
We asked what evidence the IDF have that six of the medics killed were in fact Hamas operatives, whether they will put any of their evidence into the public domain, and whether any of the soldiers involved in the incident had been withdrawn from operational duties in Gaza until their investigation is complete.
Mr Mencer did not answer those important questions directly but told an online briefing that Hamas use ambulances to travel around Gaza, and insisted six of those killed were Hamas terrorists, without providing any new evidence, and accused the international media of readily accepting Hamas’ version of events.
However, this version of events in fact came from United Nations bodies and the Palestinian Red Crescent, reputed organisations with people on the ground in Gaza itself.
The fact that Israel has already had to dramatically change its story once is why questions will remain until they provide the evidence to back up their latest version of what happened near Rafah around dawn on 23 March.
Mr Mencer said: “IDF soldiers opened fire at a distance at vehicles moving suspiciously in their direction.
“Among the dead were six Hamas terrorists – what were Hamas terrorists doing in ambulances? The incident was reported in real time to UN officials.”
He claimed there were “many documented occasions” when Hamas had used ambulances as cover.
An evacuation order was also in place at the time, which meant moving vehicles were prohibited, according to Israel.
The head of the UN’s humanitarian affairs office, Jonathan Whittall, said the 15 people were found in a “mass grave” in the sand.
He said those killed comprised eight members of the PRCS, six civil defence members and one UN employee.
Dylan Winder, from the International Federation of Red Cross and Red Crescent Societies (IFRC), said it was “outraged at the deaths” and that “even in the most complex conflict zones, there are rules”.
“They were humanitarians. They wore emblems that should have been protected. Their ambulances were clearly marked, and they should have returned to their families. They did not,” he said.
Until five weeks ago, Arturo Suarez was a professional singer, performing in the United States as he waited for his asylum claim to be processed.
Originally from Venezuela, he had entered the US through proper, legal channels.
But he is now imprisoned in a notorious jail in El Salvador, sent there by the Trump administration, despite seemingly never having faced trial or committed any crime. The White House claims he is a gang member but has not provided evidence to support this allegation.
His brother, Nelson Suarez, told Sky News he believes his brother’s only “crime” is being Venezuelan and having tattoos.
Image: Arturo Suarez, in a music video, is now in a notorious prison in El Salvador
“He is not a gang member,” Nelson says, adamantly, “I’ve come to the conclusion that it has to be because of the tattoos. If you don’t have a criminal record, you haven’t committed any crime in the United States, what other reason could there be? Because you’re Venezuelan?”
Arturo, 34, was recording a music video inside a house in March when he was arrested by immigration agents.
He was first taken to a deportation centre in El Paso, Texas, and then, it appears, put on to a military flight to El Salvador.
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Image: Nelson Suarez insists his brother Arturo is not a gang member
His family have not heard from him since. Lawyers and immigrant rights groups have been unable to make contact with any of the more than 200 Venezuelan men sent to the CECOT prison, which holds members of the MS-13 and Tren de Aragua gangs.
Tattoo clue to Arturo Suarez’s whereabouts
Nelson learned his brother is – most likely – in CECOT only because of a photograph he spotted on a news website of a group of inmates, with their hands and feet cuffed, heads shaved and bodies shackled together.
Image: A group of inmates are processed to be imprisoned in the CECOT jail in EL Salvador. Pic: Reuters
Image: Nelson Suarez believes this is his brother Arturo Suarez due to his distinctive hummingbird tattoo. Pic: Reuters
“You can see the hummingbird tattoo on his neck,” Nelson says, pointing to the picture. He says Arturo wanted a hummingbird in memory of their late mother. Arturo has 33 tattoos in total, including a piano, poems and verses from the Bible.
It could be that one, or more, of those tattoos landed him at the centre of President Trump’s anti-immigration showpiece. Nelson shows me documents which indicate that Arturo did not have a criminal record in Venezuela, Chile, Colombia or the United States, the four countries he has lived in.
Sky News contacted the White House, the Department of Homeland Security (DHS), and Immigration and Customs Enforcement (ICE) for a response to Arturo’s case but have not heard back.
In March, Donald Trump signed the Alien Enemies Act, a law from 1798 which has been invoked just three times before, in wartime.
It allows the president to detain and deport immigrants living legally in the US if they are from countries deemed “enemies” of the government. In this instance, Mr Trump claimed the Venezuelan gang Tren de Aragua had “infiltrated the United States” and was “conducting irregular warfare”.
Image: Alleged gang members imprisoned in the CECOT jail in El Salvador. Pic: Reuters
Gang symbol tattoos
Immigration officials have centred on certain tattoos being gang symbols. Immigration officers were provided with a document called the “Alien Enemy Validation Guide”, according to a court filing from the American Civil Liberties Union. The document provides a point-based system to determine if an immigrant in custody “may be validated” as a gang member.
Migrants who score six points and higher may be designated as members of the Tren de Aragua gang, according to the document. Tattoos which fall under a “symbolism” category score four points and social media posts “displaying” gang symbols are two points. Tattoos considered suspicious, according to the document, include crowns, stars and the Michael Jordan Jumpman logo.
Jerce Reyes Barrios’s story
Another of the men sent to CECOT prison is 36-year-old Jerce Reyes Barrios, who fled Venezuela last year after marching in anti-government protests. He is a former footballer and football coach.
His lawyer, Linette Tobin, told Sky News that Reyes Barrios entered the US legally after waiting in Mexico for four months for an immigration appointment and then presenting himself at the border.
Image: Jerce Reyes Barrios
She says he was detained in a maximum security prison in the US while awaiting his asylum appointment. But before that appointment happened, he was flown to the El Salvador prison.
Ms Tobin says the DHS deported Reyes Barrios because they designated him a Tren De Aragua gang member based on two pieces of evidence.
The first, she says, is a tattoo of the Real Madrid football team logo surrounded by rosary beads. She has since obtained a declaration from the tattoo artist stating that Reyes Barrios just wanted an image which depicted his favourite team.
Image: Jerce Reyes Barrios’s lawyer says he has a tattoo of the Real Madrid logo surrounded by rosary beads
The second piece of evidence, she says, is a photograph, which she shows me, of Reyes Barrios in a hot tub with friends when he was a college student 13 years ago.
He is making a gesture which could be interpreted as “rock and roll”, but which she says has been interpreted as a gang symbol.
Image: Lawyer Linette Tobin says this gesture has been interpreted as a gang symbol
Distraught family in despair
Reyes Barrios has no criminal record in his home country. “I’ve never known anything like this,” Ms Tobin says.
“My client was deported to a third country and we have no way of getting in touch with him. His family are distraught and in despair, they cry a lot, not knowing what is going on with him. We want him returned to the United States to have a hearing and due process.”
Ms Tobin says she and other lawyers representing men sent to the El Salvador prison are trying to establish a UN working group on enforced disappearances to do a wellness check on them because the prison is completely “incommunicado”.
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17 March: US migrants deported to El Salvador
Sky News contacted the DHS for comment about Reyes Barrios’s case but did not receive a response. The DHS previously issued a statement declaring that “DHS intelligence assessments go well beyond just gang-affiliated tattoos. This man’s own social media indicates he is a member of Tren de Aragua”.
Reyes Barrios has an immigration hearing scheduled for 17 April, Ms Tobin says, which the Trump administration is trying to dismiss on the grounds that he is not in the US anymore.
In the meantime, children he used to coach football for in his hometown of Machiques in Venezuela have been holding a prayer vigil for him and calling for his release.
The secretary of the DHS, Kristi Noem, visited CECOT last month and posed for photos standing in front of inmates behind bars.
Image: Department of Homeland Security secretary Kristi Noem visited CECOT in March. Pic: Reuters
“Do not come to our country illegally,” she said, “you will be removed, and you will be prosecuted.” Donald Trump had promised during his election campaign to clamp down on immigration, railing against undocumented immigrants and claiming immigrants are “poisoning the blood of our country”.
I ask Arturo Suarez’s brother, Nelson, how he felt watching Ms Noem posing in the prison, knowing that his brother might be close by.
“I feel bad,” he says, “I feel horrible, because in those images we only see criminals. With my brother, I feel it is more a political issue. They needed numbers, they said, these are the numbers, and now, let’s throw them to the lions.”
Image: Kilmar Abrego Garcia. Pic: AP
Kilmar Abrego Garcia’s story
The Trump administration has admitted that at least one man sent to the El Salvador jail was sent by “administrative error”. Kilmar Abrego Garcia, who was living in Maryland, was sent to CECOT despite a judge’s earlier ruling in 2019 that granted him legal protection to stay in the US.
The White House has alleged Garcia is an MS-13 gang member, but his lawyers argued there is no evidence to prove this.
A federal judge has ordered Garcia must be returned to the US by Monday 7 April. In a post on X, White House deputy chief of staff Stephen Miller referred to the judge as a “Marxist”, who “now thinks she’s president of El Salvador”.
White House press secretary Karoline Leavitt said: “We suggest the judge contact President Bukele because we are unaware of the judge having jurisdiction or authority over the country of El Salvador.”
Israeli airstrikes have killed more than 30 people in Gaza, including over a dozen women and children, local health officials have said.
Strikes overnight into Sunday hit a tent and a house in Khan Younis, killing five men, five women and five children, according to Nasser Hospital, which received the bodies.
Later on Sunday, at least two people were killed, and six others injured when an Israeli airstrike hit a tent in Khan Younis located outside the Nasser hospital, which was being used as a base by a number of journalists.
A number of them were among the injured, according to hospital officials.
Footage showed a journalist being engulfed by flames after his tent was hit by an airstrike. He is reported to be in a critical condition.
Image: On Sunday, at least two people were killed, and six others injured when an Israeli airstrike hit a tent in Khan Younis which was being used as a base by a number of journalists. Pic: AP
Image: Pic: AP
Image: Pic: AP
Israeli shelling killed at least four people in the Jabaliya refugee camp, according to Gaza’s Hamas-run Health Ministry.
The bodies of seven people, including a child and three women, arrived at Al Aqsa Martyrs Hospital in Deir al Balah, according to an Associated Press journalist there.
And a strike in Gaza City hit people waiting outside a bakery, killing six, including three children, according to the civil defence, which operates under the Hamas-run government.
Last month, Israel ended its ceasefire with Hamas and restarted its air and ground offensive.
It has carried out waves of strikes and seized territory in an attempt to pressure Hamas to accept a new deal for a truce and release the remaining hostages.
It has also blocked the import of food, fuel and humanitarian aid for over a month.
“Stocks are getting low and the situation is becoming desperate,” the United Nations agency for Palestinian refugees said on social media.
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3:02
Israel ‘seizing territory’ in Gaza
On Sunday night, Israel’s military ordered Palestinians to evacuate several neighbourhoods in Gaza’s Deir al Balah shortly after around 10 projectiles were fired from Gaza.
The military said around five were intercepted, and Hamas’s military arm claimed responsibility.
Police said a rocket fell in Ashkelon, an Israeli city just to the north of Gaza, and fragments fell in several other areas.
The Magen David Adom emergency service said one man was lightly injured, and the military later said it struck a rocket launcher in Gaza.
Image: A woman bakes bread in an oven in Gaza City. Pic: Reuters
Netanyahu visits Trump
It comes as Israeli Prime Minister Benjamin Netanyahu heads to the United States to meet with Donald Trump to discuss the war.
Mr Netanyahu said the pair would also discuss the new 17% tariff imposed on Israel as part of Mr Trump’s sweeping new tariffs.
“There is a very large queue of leaders who want to do this with respect to their economies. I think it reflects the special personal connection and the special connection between the United States and Israel, which is so vital at this time,” Mr Netanyahu said during a visit to Hungary.
The war between Israel and Hamas began when Hamas-led militants invaded Israel on 7 October 2023 and killed around 1,200 people and took 251 hostage.
Some 59 hostages are still being held in Gaza, with 24 still believed to be alive.
Israel’s offensive has killed at least 50,695 Palestinians, according to Gaza’s Hamas-run health ministry, which does not differentiate between civilians or combatants, with another 115,338 wounded.
Israel says it has killed around 20,000 militants.