The B-52 Stratofortress bomber, designed and first fielded to deliver nuclear strikes on the Soviet Union during the Cold War, has dropped its first bombs on the Islamic State, the Pentagon announced Wednesday.

A contingent of B-52H Stratofortresses that arrived at Al Udeid Air Base in Qatar this month began bombing around the northern Iraqi city of Mosul on Monday. It is the bomber’s first deployment to the Middle East since the Persian Gulf War. The huge aircraft is an iconic symbol of American air power and its presence over Islamic State-held territory will be a boost for Iraqi and Kurdish forces preparing to take back one of the Islamic State’s biggest strongholds in Iraq.

Before the B-52’s arrival in the region, B-1B Lancers served as the primary heavy bombers tasked with carrying out airstrikes against the Islamic State in Iraq and Syria. The Lancers returned to the United States earlier this year to receive upgrades to their avionics, leaving a gap between their departure and the B-52’s arrival.

The lumbering eight-engine bombers delivered strikes against al-Qaeda and the Taliban during the opening salvos of the war in Afghanistan. In Vietnam, they were famous for their carpet bombing runs against the North Vietnamese, known as Arc Light missions. B-52s can carry 70,000 pounds of conventional munitions, including GPS guided bombs and air-launched cruise missiles. Their large size allows for long periods airborne, however their targeting system is cumbersome. For close air support, B-52s rely on targeting coordinates generated from latitude and longitude, while most aircraft used in support of ground operations locate their targets with grid coordinates.

The B-52s, along with other aircraft hitting the Islamic State, will be able to drop their ordnance on targets faster, said Col. Steve Warren, a spokesman for the U.S.-led campaign against the militant group. Changes in the rules of engagement, which were first reported by USA Today, mean U.S. jets and unmanned aircraft will now have a shorter approval process for dropping munitions. This means lower-ranking commanders will have more authority when it comes to when and where their forces can drop bombs.

“The more authorities that are delegated down, the more rapidly we are able to respond,” Warren told reporters in a televised briefing Wednesday. Warren emphasized that he thinks this will not translate into more civilian casualties and said that more complicated strikes will still require higher approval.

The Pentagon has admitted to a small number of civilian casualties in the nearly two-year-old air war against the Islamic State, often conducting long investigations to verify casualty claims., a nonprofit organization that uses social media and firsthand accounts to monitor airstrikes in Iraq and Syria, estimates that, at a minimum, the U.S.-led coalition has killed more than 1,000 civilians in Iraq and Syria since August 2014.