Multiple rockets hit near the U.S. embassy in Iraq's capital early Sunday, an American military source said, the latest in a flurry of attacks against U.S. assets in the country.

It was the 19th attack since October to target either the embassy or the roughly 5,200 U.S. troops stationed alongside local forces across Iraq. The attack came a day after a senior U.S. official announced the resumption of joint operations between the U.S.-led coalition and Iraqi security forces.

The attacks were never claimed by an organization, but the U.S. has pointed the finger at Iran-backed groups within the Hashed al-Shaabi, a military network officially incorporated into Iraq's state security forces.

The attack was the latest in a recent series of rocket and mortar strikes on Iraqi bases housing U.S. troops. On Thursday, a mortar shell exploded in the K1 Iraqi military airbase in Kirkuk province in northern Iraq. No casualties were reported, Iraqi security officials said. An Iranian missile attack on Iraq's Ain al-Asad airbase on Jan. 8 injured dozens of U.S service members. The attack was in retaliation for the U.S. drone strike in Baghdad that killed Iran's most powerful general, Qassem Soleimani, on Jan. 3. The U.S. Embassy in Baghdad has also been a flashpoint amid wider U.S.-Iran tensions in the region, which have played out inside Iraq in recent weeks. Iraqi supporters of an Iran-backed militia stormed the embassy compound Dec. 31, smashing the main door and setting fire to the reception area.