The United States launched a second round of airstrikes on Iran into Thursday morning after US President Donald Trump warned that Tehran would “pay the price” for stalled negotiations, and Iran responded with strikes targeting Bahrain, Kuwait and Jordan.The new US assault across multiple Iranian cities came as efforts to negotiate an end the war again appeared stuck, with Iran insisting it would maintain its chokehold on the Strait of Hormuz, which has disrupted global energy supplies and sent oil prices higher. The American attack appeared more intense and wider than the day before, but Iran released little information on the extent of the damage.Kuwait closed its airspace for several hours because of the Thursday morning attack, but did not elaborate on any damage. Jordan said it intercepted 20 Iranian missiles fired toward an area that is home to an air base hosting US troops, though no one was hurt.And in Bahrain, the Interior Ministry said an 11-year-old girl had been hurt and cars and homes were damaged by “falling debris” from interceptions responding to the Iranian attack.The third back-and-forth strikes this week have tested a two-month shaky ceasefire. The first were attacks between Iran and Israel on Sunday into Monday, followed by the two rounds of fire between America and Tehran.Trump has urged Iran to sign a deal to end the war and suggested earlier this week that an agreement could be reached in days.But Iran has proved resilient despite weeks of heavy bombing. It is betting that its ability to effectively close the Strait of Hormuz -- a crucial passageway for oil and natural gas -- gives it a strong bargaining chip.Still, both countries seem to be looking for a way to end the conflict -- if they can manage to sell it as a win at home.Israeli Prime Minister Benjamin Netanyahu also appears intent on pursuing goals that make compromise harder: the collapse of Iran's theocratic government, the elimination of its nuclear program, and the destruction of the Iranian-allied Hezbollah militant group in Lebanon.