Two battalions of Revolutionary Guards were reported to be operating in Iraq trying to combat the 2014 Northern Iraq offensive. The IRGC is considered to be a principle backer of the Popular Mobilization Forces, a loose coalition of Shi'a militias allied with the Iraqi government in its fight against the Islamic State of Iraq and Syria (ISIS). In addition, Major General Qasem Soleimani was an instrumental force in the Iranian ground mission in Iraq against ISIS, purportedly planning the Second Battle of Tikrit. In December 2014, Brigadier General Hamid Taqavi, a veteran of the 1980–1988 Iran–Iraq War, was killed by snipers in Samarra. In May 2017, Shaaban Nassiri, a senior IRGC commander was killed in combat near Mosul, Iraq. In December 2019, the U.S. Air Force conducted airstrikes on weapons caches and facilities of the IRGC-sponsored militant group Kata'ib Hezbollah. In retaliation, the group attacked the U.S. Embassy in Baghdad in the Green Zone.