Iraqi units. However, in April, the Congressional Research Service reported that only around 4000 U.S. forces were embedded with Iraqi units at a rate of 10 per battalion. Former U.S. Army analyst Andrew Krepinevich argued that the roughly twelve advisors per Iraqi battalion (approximately 500 troops) was less than half the sufficient amount needed to efficiently implement the combat advisory effort. Krepinevich argues that officers try to avoid taking on advisory tasks due to the US Army's practice of prioritising the promotion of officers that have served with a U.S. unit over ones that have served with foreign forces. Advisors remained after all U.S. combat brigades left Iraq in August 2010. These troops were required to leave Iraq by 31 December 2011 under an agreement between the U.S. and Iraqi governments. 2014–2016 In the summer of 2014, large elements of the Iraqi army were routed by a much smaller and less well-equipped force from the Islamic State. "[N]ineteen Iraqi Army brigades and six Federal Police brigades disintegrated, a quarter of Iraq's security forces. These losses comprised all of the Ninawa-based 2nd and 3rd Iraqi Army divisions; most of the Salah al-Din-based 4th Iraqi Army division; all of the Kirkuk-based 12th Iraqi Army division; plus at least five southern Iraqi Army brigades that had previously been redeployed to the Syrian border." Islamic State managed to conquer large swaths of Al Anbar Governorate and Iraq's second largest city, Mosul. Budget problems continued to hinder the manning of combat support and combat service support units. The lack of soldiers entering boot camp is forcing Iraqi leaders at all levels to face the dual challenge of manning and training enabler units out of existing manpower. In the 2015 Pentagon budget, a further $1.3 billion has been requested to provide weapons for the Iraqi Army. However, the New York Times reported that "some of the weaponry recently supplied by the army has already ended up on the black market and in the hands of Islamic State fighters". The same November 2014 article contended that corruption is endemic in the Iraqi Army. It quoted Col. Shaaban al-Obeidi of the internal security forces, who told the paper's David D Kirkpatrick: "Corruption is everywhere." The article claimed that one Iraqi general is known as "chicken guy" because of his reputation for selling the soldiers' poultry provisions. In late June 2014, after the large-scale Islamic State of Iraq and