An already shaky ceasefire between the United States and Iran appeared to be on the verge of collapse Monday, as the United Arab Emirates said it was under attack from Iranian drones and missiles and the U.S. reportedly said it sank Iranian boats in the Strait of Hormuz.
President Donald Trump, in a Fox News interview later Monday, warned Iran that it will be "blown off the face of the earth" if it targets U.S. ships that are protecting commercial vessels transiting the Strait of Hormuz.
Adm. Brad Cooper, who leads U.S. Central Command, said in a call with reporters Monday afternoon that American forces eliminated six small Iranian boats that were attempting to interfere with commercial shipping, Reuters reported.
Tehran's state media denied that its boats had been sunk.
Stock market indices fell, and oil prices rose on news of the UAE attacks, raising investors' fears that the war's impact on the global economy could be exacerbated or prolonged.
The White House did not immediately respond when asked whether the reported attacks, which led the UAE to activate its missile alert system for the first time since the ceasefire began on April 8, would violate that truce.
The UAE's Defence Ministry, in a translated post on its official X account, said Monday morning that its air defenses "are currently dealing with missile attacks and incoming drones from Iran."
The ministry said that "the sounds heard in various parts of the country are the result of the UAE air defense systems intercepting ballistic missiles, cruise missiles, and drones."
In an earlier post, the ministry said that three "loitering munitions" were "intercepted over the country's territorial waters," while a fourth missile "fell into the sea."
The UAE is located on the southern rim of the Persian Gulf, a major chokepoint for the shipment of oil.
A social media account associated with Iran's Islamic Revolutionary Guard Corps later Monday appeared to confirm that it launched the attacks against the UAE.
In translated messages on Telegram, the account posted visuals of what it said were drone and missile attacks carried out by the "IRGC Cyber Corps." One post claimed to show the aftermath of a drone attack on UAE's Port of Fujairah, while another included a video purporting to a ship on fire following a missile strike.
An alert issued to phones in Dubai and Abu Dhabi on Monday evening local time warned people, "Due to the current situation, potential missile threats, immediately seek a safe place in the closest secure building."
— CNBC's Emma Graham and Megan Cassella contributed to this report.
