The rocket that exploded Sunday outside the U.S. embassy in Baghdad is of a design trafficked by Iran and used by Middle Eastern terrorist groups.

While it is unclear who was responsible for firing or supplying the Katyusha rocket, weapons of the same type were seized by Yemeni authorities on an Iranian ship in 2013. Iran is known to support terrorist groups in the region both financially and with arms, and Iranian forces are known to field Katyusha rockets.

Brig. Gen. Yahya Rasoul said that the Iraqi military believed the rocket was fired from east Baghdad, where many Iran-backed Shiite militias are based.

The explosion came as tensions between the United States and Iran continue to rise. President Trump tweeted a warning to Iran shortly after the explosion occurred. "If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!" he said.

No casualties have been reported from the attack, the first in Baghdad's highly-secured Green Zone since September. Many foreign and Iraqi diplomats and officials are based in the Green Zone, though nonessential U.S. embassy staff were ordered out of Iraq last week.

With a range of up to 25 miles, the Katyusha is a cheap and rudimentary weapon. Originally of Russian design, the Katyusha was first deployed by the Soviet Red Army in World War II. Its use has continued after the collapse of the Soviet Union, with multiple countries fielding it in their national armies. It is also a weapon of choice for Iranian-sponsored terrorist organizations, including Hamas and Hezbollah.

U.S. and British forces in Iraq and Syria were put on high alert last week after intelligence reports warned of a potential Iranian threat. The United States has deployed the USS Abraham Lincoln aircraft carrier strike group, an amphibious warfare ship, a contingent of B-52 bombers, and a Patriot missile defense battery to the region.