DUBAI/RIYADH – Yemen’s Iran-aligned Houthis said on Monday that they would impose a naval blockade on Saudi Arabia, opening a potential new front against the United States in its war with Iran and raising the threat to global energy supply and trade beyond the Persian Gulf.

The escalation comes after one of the deadliest periods in the war for U.S. troops. The Pentagon on Monday identified two U.S. soldiers who were killed when Iran attacked an American base ​in Jordan on Friday, while they also said they had found unidentified remains that could be those of a third soldier reported as missing in action.

Separately, a fourth service member was killed in northern ‌Iraq ‌during the “controlled detonation of unexploded ordnance from a downed Iranian one-way attack drone.” After the Houthis announced their blockade, the Saudi-led coalition in Yemen said in a statement that ​it would respond to them with force, and also that it began implementing protection measures for its ships moving through the Bab el-Mandeb Strait, a key export route for Saudi oil after the effective closure of the Strait of Hormuz.