(Bloomberg) – Iran attacked the United Arab Emirates for the first time in almost a month on Monday, as tensions between the U.S. and Islamic Republic rose.

The UAE said it intercepted Iranian cruise missiles fired at different parts of the country, fracturing an uneasy calmness since a ceasefire between Tehran and the U.S.-Israel alliance took hold around April 8.

An oil terminal part-owned by Vitol Group was attacked in the port city of Fujairah, according to people familiar with the matter, who asked not to be identified because they weren't authorized to discuss the matter publicly. Fujairah's media office said a large fire started at an oil industrial zone after a drone attack from Iran. Three people were injured, it said.

Oil jumped, with Brent crude trading almost 6% higher at roughly $114 a barrel.

The fresh strikes underscore the fragility of the truce. The war began in late February with U.S. and Israeli strikes on Iran, which retaliated by firing thousands of missiles and drones at Israel and Gulf Arab states. Thousands of people have been killed, mostly in Iran and Lebanon, where Israel is fighting a parallel conflict against Iran-backed Hezbollah militants.

The UAE was targeted more than any other country. Its Foreign Ministry described the latest strikes as a "dangerous escalation," saying the country "will not tolerate any threat to its security and sovereignty under any circumstances, and that it reserves its full and legitimate right to respond to these unprovoked attacks." The alerts in the UAE came hours after a tanker owned by ADNOC was fired upon by Iranian drones near the Strait of Hormuz.

They also came shortly after the U.S. began what President Donald Trump said was a "humanitarian" effort to get ships stranded in the Persian Gulf out via the strait. As part of that, two U.S.-flagged merchant ships have so far transited the strait, the U.S. military said.

Iran warned it would attack U.S. forces if they came near Hormuz and told commercial ships not to cross the waterway without seeking permission.