The U.S. struck Iran on Friday 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.

A ceasefire between the U.S. and Iran went into effect earlier this month and called for an immediate end to military operations from both countries and their allies.

The U.S. has struck Iran to respond to a drone attack a day earlier on a cargo ship in the Strait of Hormuz, a provocation that President Donald Trump said violated the ceasefire.