Oil prices jumped on Monday after Iran and Israel exchanged strikes, casting fresh doubt on the future of a fragile cease-fire in the Middle East and stoking fears of an escalation in violence.

The strikes came after Israel attacked the outskirts of Beirut, targeting Hezbollah, the Iranian-backed militant group. Iran retaliated by firing a barrage of ballistic missiles, which prompted a counterattack from Israel. The attack and counterattack are the first such hostilities since a cease-fire paused the war with Iran two months ago.

President Trump said on Monday that Israel and Iran should “immediately stop” the strikes and suggested that a more enduring peace deal was in the works. The rise in oil prices moderated somewhat during a lull in the fighting.