DUBAI, United Arab Emirates (AP) — Both Bahrain and Kuwait came under heavy attack early Wednesday as Iran retaliated over U.S. strikes targeting it and the reimposed blockade.

Bahrain sounded its missile alert siren, while Kuwait’s military said its air defenses were firing to shoot down incoming missiles and drones.

Both countries host U.S. military forces and have been repeatedly targeted by Iran as tensions have mounted over the Strait of Hormuz.

The U.S. military also said Tuesday that it has reimposed its blockade of Iranian ports in response to Iran’s attacks on commercial ships in the Strait of Hormuz, as the interim ceasefire deal unravels and concerns grow about a return to all-out war.

The U.S. first imposed the blockade in mid-April and then lifted it in mid-June, a day after the signing of the interim deal aimed at permanently ending the war. The deal set a 60-day timeline to also negotiate an agreement on Iran’s nuclear program, but talks have stalled as fighting over the strait has intensified.

When U.S. President Donald Trump announced the return of the blockade Monday, he also said he would impose a 20% fee on ships passing through the strait. But he dropped the plan to collect fees hours before resuming the blockade, citing requests from allies in the Gulf.

The interim peace agreement was supposed to reopen a waterway that is key to world energy supplies and give negotiators time to hammer out a permanent end to the war. Instead, fighting has once again engulfed the region and threatened the global economy.

The U.S. carried out another wave of strikes ahead of reimposing the blockade, the U.S. military’s Central Command said. Iran’s deputy foreign minister for legal and international affairs, Kazem Gharibabadi, said in an interview aired Tuesday by IRIB, Iran’s state broadcaster, that the U.S. was seeking to prevent Tehran from exercising what he described as “effective sovereignty” over the strait.