U.S. Steel shares jumped on Monday after President Donald Trump approved its controversial merger with Japan’s Nippon Steel.

U.S. Steel shares were last up about 5% in premarket trading.

Trump issued an executive order on Friday that allowed U.S. Steel and Nippon to finalize their merger so long as they signed a national security agreement with the U.S. government. The companies said they signed the agreement with the government, completing the final hurdle for the deal.

U.S. Steel said the national security agreement includes a golden share for the U.S .government, without specifying what powers the government would wield with its share. Trump said on Thursday that the golden share gives the U.S. president “total control.”

Typically, golden shares allow the holder veto power over important decisions the company makes. Pennsylvania Sen. Dave McCormick told CNBC in May that the golden share will give the U.S. government control of several board seats and ensure production levels aren’t cut.

Trump has avoided calling the transaction a merger, describing the deal instead as a “partnership.” U.S. Steel confirmed in a regulatory filing Monday that the company will become a wholly owned subsidiary of Nippon Steel North America.

“All regulatory approvals required for the completion of the Transaction have been received,” U.S. Steel said in a filing with the Securities and Exchange Commission on Monday. “The Transaction remains subject to the satisfaction of customary closing conditions, and is expected to be completed promptly.”

Tehran will “pay the price” for its fresh missile onslaught against Israel, the Jewish state’s defense minister warned Monday, as markets braced for a fourth day of ramped-up conflict between the regional powers.

Fire exchanges have continued since Israel’s Friday attack against Iran, with Iranian media reporting Tehran’s latest strikes hit Tel Aviv, Jerusalem and Haifa, home to a major refinery. CNBC has reached out to operator Bazan for comment on the state of operations at the Haifa plant, amid reports of damage to Israel’s energy infrastructure.

Iran’s Revolutionary Guard said overnight it deployed “innovative methods” that “disrupted the enemy’s multi-layered defense systems, to the point that the Zionist air defense systems engaged in targeting each other,” according to a statement obtained by NBC News.

Israel has widely depended on its highly efficient Iron Dome missile defense system to fend off attacks throughout regional conflicts — but even it can be overwhelmed if a large number of projectiles are fired.

The fresh hostilities are front-of-mind for investors, who have been weighing the odds of further escalation in the conflict and spillover into the broader oil-rich Middle East, amid concerns over crude supplies and the key shipping lane through the Strait of Hormuz connecting the Persian Gulf and the Gulf of Oman.

Oil prices retained the gains of recent days and at 09:19 a.m. London time, Ice Brent futures with August delivery were trading at $73.81 per barrel, down 0.57% from the previous trading session. The Nymex WTI contract with July expiry was at $72.7 per barrel, 0.38% lower.

Elsewhere, however, markets showed initial signs of shrugging off the latest hostilities early on Monday.

Spot prices for key safe-haven asset gold retreated early morning, down 0.42% to $3,417.83 per ounce after nearly notching a two-year-high earlier in the session, with U.S. gold futures also down 0.65% to $ 3,430.5

Tel Aviv share indices pointed higher, with the blue-chip TA-35 up 0.99% and the wider TA-125 up 1.33%.

European stock markets opened higher Monday, meanwhile, and U.S. stock futures were also in the green.

Luis Costa, global head of EM sovereign credit at Citigroup Global Markets, signaled the muted reaction could be, in part, attributed to hopes of a brisk resolution to the conflict.

“So markets are obviously, you know, bearing in mind all potential scenarios. There are obviously potentially very bad scenarios in this story,” he told CNBC’s “Europe Early Edition” on Monday. “But there is still a way out in terms of, you know, a faster resolution and bringing Iran to the table, or a short continuation here, of a very surgical and intense strike by the Israeli army.”

Accusing Tehran of targeting civilians in Israel to prevent the Israel Defense Forces from “continuing the attack that is collapsing its capabilities,” Israeli Defense Minister Israel Katz, a close longtime ally of Prime Minister Benjamin Netanyahu, said in a Google-translated social media update that “the residents of Tehran will pay the price, and soon.”

The IDF on Sunday said it had in turn “completed a wide-scale wave of strikes on numerous weapon production sites belonging to the Quds Force, the IRGC and the Iranian military, in Tehran.”

CNBC could not independently verify developments on the ground.

The U.S.’ response is now in focus, given its close support and arms provision to Israel, the unexpected cancellation of Washington’s latest nuclear deal talks with Iran, and President Donald Trump’s historically hard-hitting stance against Tehran during his first term.

Trump, who has been pushing Iran for a deal over its nuclear program, has weighed in on the conflict, opposing an Israeli proposal to kill Iran’s supreme leader, Ayatollah Ali Khamenei, according to NBC News.

Discussions about the conflict are expected to take place during the ongoing meeting of the G7, encapsulating Canada, France, Germany, Italy, Japan, the U.K. and the U.S., along with the European Union.

— CNBC’s Katrina Bishop contributed to this report.