The U.S. military announced that it had launched strikes against Iran Tuesday evening, marking the latest exchange of blows between the countries amid a fragile ceasefire.

In a post on X, U.S. Central Command announced that American forces had begun launching a “series of powerful strikes against Iran to impose heavy costs for targeting and attacking commercial shipping crewed by innocent civilians in an international waterway.

“The U.S. strikes are in response to Iranian attacks on three commercial vessels that were transiting the Strait of Hormuz,” the post continued. “Iran’s demonstrated aggression was unwarranted, dangerous, and a clear violation of the ceasefire.”

The latest round of violence could further imperil U.S. negotiations over fully reopening the Strait of Hormuz and reviving talks over Iran’s nuclear program. 

Israel has treated the U.S.-Iran negotiations warily, chafing especially at the proposed imposition of terms of engagement with Iran-backed Hezbollah in Lebanon.

Iran has not claimed responsibility for the attacks on commercial vessels. Qatar’s Foreign Ministry spokesperson Majed Al Ansari wrote in a post on X that the country held Iran “fully legally responsible” for an attack on the Qatari ship Al-Rekayyat in the strait.

“We demand that the Islamic Republic of Iran immediately cease all practices that undermine regional security or threaten the safety of international maritime navigation, & refrain from endangering global energy supplies & the resources of the countries of the region in pursuit of narrow interests,” Al Ansari wrote.

Saudi Arabia’s Foreign Affairs Ministry also condemned Iran’s alleged attack on a Saudi tanker, in a post on X shortly before the U.S. strikes were announced.

“The Kingdom affirms that these reprehensible attacks constitute an assault on the security and safety of international navigation and on the security of global energy supplies,” the post read.

The strikes come over a week since the last known round of U.S. strikes on the country late last month, which followed Iranian attacks on both Bahrain and Kuwait.