Today, U.S. forces stationed in Kabul dropped the largest non-nuclear bomb in U.S. history on eastern Afghanistan, targeting Islamic State-controlled tunnels and caves. An MC-130 aircraft dropped the weapon, called a GBU-43/B Massive Ordnance Air Blast Bomb (MOAB), just after 7:30 local time Thursday evening, according to a CNN report. The bomb weighs 21,600 pounds, or 11 tons, is guided by GPS and ranks as the most powerful non-nuclear bomb in America’s arsenal. Upon its development in the early 2000s, the Pentagon had to review its international legality. Today marks the first time it’s been used.

“The United States takes the fight against ISIS very seriously and in order to defeat the group we must deny them operational space, which we did,” White House Press Secretary Sean Spicer said. He added that the munition “targeted a system of tunnels and cave that ISIS fighters use to move around freely.”

Spicer refused to say whether or not President Donald Trump specifically ordered the use of the bomb or whether Afghanistan commanding officer General John Nicholson made the decision. It’s not likely the U.S Army would deploy such a weapon without presidential approval.

Internet reaction to the news was swift.