The U.S. Embassy in Baghdad was the target of a rocket attack late Sunday, days after the Trump White House ordered American diplomatic personnel to pull out of the country.

Iraqi military officials confirmed Sunday a single Katyusha rocket landed near the parade grounds inside the heavily-fortified Green Zone in the Iraqi capital, which is home to the U.S. embassy as well as the main headquarters for the American-led coalition battling the Islamic State.

But eyewitnesses claim a second rocket also landed inside the Green Zone, according to unconfirmed reports.

No casualties were reported and no group has claimed responsibility for the attack, the first against a U.S. diplomatic post in Iraq since the American mission in the southern port city of Basra was hit last September.

“We are aware of an explosion in the International Zone outside of the U.S. Embassy compound in Baghdad on May 19. There were no U.S. or coalition casualties, and Iraqi Security Forces are investigating the incident,” Capt. Bill Urban, U.S. Central Command spokesman said in a statement Sunday night.

Mr. Trump took to Twitter hours after the attack, warning Tehran against any action against U.S. interests in Iraq or elsewhere.

“if Iran wants to fight, that will the official end of Iran. Never threaten the United States again,” he wrote.

State Department officials acknowledged in a separate statement that no entity had yet taken responsibility for the attacks, but that Washington would hold Tehran accountable, should its proxies in Iraq be shown as responsible.

“We have made clear over the past two weeks and again underscore that attacks against U.S. personnel and facilities will not be tolerated and will be responded to in a decisive manner,” the statement says.

Sunday’s rocket attacks come days after the Trump administration ordered the withdrawal of all non-essential personnel from U.S. outposts in Baghdad, after after U.S. intelligence had picked up communications related to the movement of rockets in Iraq by Iran-backed militias in the city.

But British Maj. Gen. Chris Ghika, the No. 2 officer with the U.S.-led anti-ISIS coalition told reporters at the Pentagon on Tuesday there has been “no increased threat” from Tehran’s proxies in Iraq or Syria. U.S. Central Command spokesman Capt. Bill Urban pushed back hard on Gen. Ghika’s assessment, saying his assessment runs “counter to the identified credible threats available to intelligence from U.S. and allies.”

Administration officials already ordered the U.S.S. Abraham Lincoln aircraft carrier strike group into the Persian Gulf earlier this month, in response to reportedly imminent threats to U.S. military personnel in the region by Iranian forces.