The US struck Iran on Saturday in response to a drone attack a day earlier on a cargo ship in the Strait of Hormuz. It’s the most significant test yet to an interim understanding reached a week ago by the two countries to begin working to end their months-long war and reopen the pivotal waterway.

US President Donald Trump said the drone attack violated the ceasefire. “I don’t like the fact that they took a shot yesterday, actually four of them,” Trump said. When asked why there would be strikes when Trump has insisted talks with Tehran are going well, Trump said of Iran, “They’re a little bit different.”