State Department tells Americans worldwide to 'exercise increased caution'

A tanker was struck by an "unknown" projectile off the coast of Fujairah, United Arab Emirates, early on Tuesday morning, according to U.K. Maritime Trade Operations, a marine tracker.

The ship, which was anchored at the time, was about 23 nautical miles off the coast, UKMTO said in a warning.

UKMTO said in an advisory late on Monday that the threat environment remained critical near the Strait of Hormuz, a vital shipping route that Iran has threatened to attempt to close to most marine traffic.

"Since the start of the hostilities on 28 February, at least twenty maritime incidents involving commercial vessels and offshore infrastructure have been reported in the Arabian Gulf, Strait of Hormuz, and Gulf of Oman," UKMTO said in the advisory.

Leaders of Canada, France, Germany, Italy and the United Kingdom issued a joint statement expressing deep concern over the escalating conflict between Israel and Hezbollah in Lebanon.

The nations condemned attacks on civilians and called for immediate de-escalation as well as “meaningful engagement … to negotiate a sustainable political solution.”

More Iranian strikes were reported across the region on Monday, including in Abu Dhabi, Qatar, Kuwait, Saudi Arabia and Israel.

Two-hundred U.S. troops have been wounded in the war with Iran so far, including 10 service members who have been “seriously wounded, according to Central Command spokesperson Capt. Tim Hawkins.

Out of the 200 injured, 180 troops have returned to duty, he said.

Wounds include burns, traumatic brain injuries and shrapnel wounds, according to a U.S. official.

Most attacks wounding U.S. troops have been from one-way Iranian attack drones, Joint Chiefs of Staff Chairman Gen. Dan Caine said last week.

-ABC News’ Steven Beynon