American drones fired more ammunition last year than manned warplanes for the first time, according to new data analyzed by Reuters. The news comes three years after U.S. President Barack Obama said that a drawdown of U.S. military forces after 2014 would “reduce the need for unmanned strikes.”

The data shows just how much American forces have come to rely on the unmanned vehicles to carry out missions in the Middle East and abroad, even while human rights organizations and some foreign governments have raised concerns over what they call an unnecessary amount of civilian casualties.

“In recent months it's definitely flowed more,” Lieutenant Colonel Michael Navicky, who commands the Air Force’s 62nd Expeditionary Reconnaissance Squadron, said. “We've seen increased weapons deployment in the past few months, and the demand is insatiable.”

Drone account for a huge amount of air strikes, proportionally, compared to just five years ago, according to the data reviewed by Reuters, making up 56 percent of air attacks in 2015 compared to 5 percent in 2011. The total number of bombs and missiles released in 2015 is almost double the number released by drones during the so-called “surge” when NATO had more than 100,000 troops in Afghanistan after 2009 — though it is also about half the number of weaponry released in 2014.

The use of drones to carry out American military interests has been a very divisive issue. While those in favor say the drones reduce risk for U.S. troops and requires less manpower in the region, critics say the tools — which could theoretically be controlled from anywhere in the world — cause unnecessary civilian casualties. There is some evidence that criticism is valid: An October review of unmanned aerial attacks found 90 percent of the people killed in then-recent strikes weren’t the target.