Iran retaliated against U.S. air and cruise missile strikes as hostilities escalated Thursday with attacks against Kuwait and Bahrain in renewed fighting after U.S. President Donald Trump warned that Tehran would “pay the price” for stalled negotiations.

The exchange came shortly after the U.S. launched a second round of airstrikes overnight Thursday. Bahrain is the headquarters of the U.S. Navy’s 5th Fleet.

The new assault across multiple Iranian cities came as efforts to negotiate an end the war appeared to have stalled, with Iran insisting it would maintain its grip on the Strait of Hormuz. Talks have also faltered because of Israel’s attacks against the Iranian-allied Hezbollah militant group in Lebanon. On Monday, Iran and Israel targeted each other.

In a first exchange of missile fire from Iran and airstrikes by the U.S. on Wednesday, Iranian missiles were launched at missiles at Bahrain, Kuwait and Jordan. Those came in the wake of American strikes in reprisal for the shooting down of a U.S. helicopter in the strait.

The U.S. Central Command said it completed its latest round of airstrikes just before the sun rose Thursday in Iran. It said the strikes targeted military surveillance, communications and air defense sites

and were carried out by the U.S. Air Force, Marines and Navy. It did not elaborate on the damage done by the strikes.

Explosions from the strikes echoed around Iran’s capital, Tehran, as well as in the port city of Bandar Abbas and other southern areas along the strait.

Iran’s says US attacks have rendered ceasefire meaningless

Iran’s Foreign Ministry issued a statement Thursday saying the U.S. attacks had “effectively rendered the ceasefire ... meaningless,” without saying it was abandoning it.