The U.S. targeted Iran on Friday in response to Iran's earlier drone strikes.
President Donald Trump announced "major combat operations" against Iran on Feb. 28, with massive joint U.S.-Israeli strikes targeting military, government and infrastructure sites.
Delegations from the United States and Iran arrived over the weekend at the Bürgenstock resort in Switzerland, where they entered negotiations aimed at a war-ending deal based on a memorandum of understanding signed last week by both countries.
The U.S. strikes against Iran involved six U.S. aircraft attacking four targets, a U.S. official told ABC News.
The official said those targets included missile, drone and radar sites along the Iranian coastline.
-ABC News' Steven Beynon
Following Friday's strikes, Vice President JD Vance emphasized that Iran signed a ceasefire agreement and "can pick up the phone" if it has any issues with the memorandum of understanding, in a post on social media.
"Iran signed a ceasefire agreement. We have honored it. If they have disagreements about how the MOU is being applied, they can pick up the phone. But violence will be met with violence," he said.
Vance was in Switzerland earlier this week to negotiate the implementation of the MOU with Iran and mediators.
-ABC News' Hannah Demissie
Friday's airstrikes against Iran mark the first U.S. military strikes on Iranian targets since the memorandum of understanding was signed on June 17, and the first test of whether the peace process it launched can withstand direct attacks between its signatories.
The strikes were designed with the goal of having a large enough scope to send a strong message on freedom of navigation through the Strait of Hormuz and provide a "course correction," but limited enough to avoid restarting the conflict and significantly derailing diplomacy, a U.S. official said -- adding the caveat that whether or how Iran chose to respond would play a big part in that.
The official said there was initially some debate within the administration over whether it was necessary to launch a military response to Iran's drone strike on the Singapore-flagged cargo ship, but that chilling effect on traffic in the strait and Tehran's messaging on managing the waterway drove the decision.
On U.S.-Iran negotiations, working-level groups have been continuing to work on key areas, and a fresh round of technical talks is currently scheduled to resume at the beginning of next week in Switzerland.
-ABC News' Shannon Kingston
The retaliatory U.S. airstrikes against Iran are over, according to a U.S. official. They lasted about an hour.
The U.S. military response to Thursday's Iranian drone attack on the container ship is limited to these "powerful" strikes for now, according to a U.S. official.
-ABC News' Luis Martinez
