Iraqi forces said they thwarted a third attempt by the Islamic State of Iraq and Syria (ISIS) militants to break through their defensive lines east of the city of Ramadi overnight on Thursday. Police and pro-government Sunni fighters exchanged mortar and sniper fire with the insurgents across the new frontline in Husaiba al-Sharqiya, about halfway between Ramadi and a base where a counter-offensive to retake the city is being prepared. Ramadi fell to the militants on Sunday in the most significant setback for Iraqi security forces in nearly a year, calling into question the U.S.-led strategy to "degrade and destroy" the militant group. The militants are now seeking to consolidate their gains in the surrounding province of Anbar by pushing east towards the Habbaniya base where Iraqi security forces and Shi'ite paramilitaries are massing. "Daesh is desperately trying to breach our defenses but this is impossible now," Police major Khalid al-Fahdawi said, referring to ISIS. "We have absorbed the shock and more reinforcements have reached the frontline. They tried overnight to breach our defenses but they failed. Army helicopters were waiting for them." Habbaniya is one of only a few remaining pockets of government-held territory in Anbar, and lies between Ramadi and the town of Falluja, which has been controlled by ISIS for more than a year. Local officials say the militants want to join up the two towns and overrun the other remaining government holdouts, strung out along the Euphrates river valley and the border with Jordan and Saudi Arabia. Government forces backed by Shi'ite militias have meanwhile been building up at a base near Ramadi in preparation for a counterattack to retake the city. The official said Iraqi forces had not totally collapsed in Ramadi, as they did in Iraq's second city of Mosul last year, and at least some managed to retreat and were now regrouping.

The United States plans to deliver 1,000 anti-tank weapons to Iraq in June to combat ISIS suicide bombings like those that helped the group seize Ramadi, a senior U.S. State Department official said on Thursday. The United States decided to supply Iraq with anti-tank weapons when Iraq's prime minister visited Washington in April and plans to deliver 1,000 of the shoulder-fired AT4 systems in early June, the official told reporters.

The U.S. military is still trying to determine the details surrounding the fall of Ramadi. General Martin Dempsey, the top U.S. military officer, was quoted by Defense Department media on Wednesday saying the Iraqi commander on the ground made "what appears to be a unilateral decision to move to what he perceived to be a more defensible position." Dempsey, according to DoD News, said the commander was concerned bad weather precluded U.S.-led air support. While the possibility of Shi'ite militias fighting in Sunni majority Anbar has raised fears of renewed sectarian violence, the official stressed that both Anbar's provincial council and the central government backed the decision to deploy them. The use of the Shi'ite militias, some of which have close ties to Iran, poses a problem for Washington, which is engaged in nuclear negotiations with Tehran even as it is seeking to contain Iranian influence in Syria, Yemen and Iraq.

The official said the Shi'ite militias had to be under Iraqi control and said Baghdad was carefully weighing which units to deploy where to minimize the chances of sectarian conflict. He also said Iraqi command and control was vital to prevent U.S.-led air strikes from hitting the militias.