President Trump is outpacing his predecessor in the number of U.S. drone strikes abroad and has made it easier for the CIA to use the craft to eliminate targets, according to a new study released Thursday — but specialists warn the use of the unmanned killing machines remains shrouded in secrecy with rules of engagement that haven’t been publicly explained.

The comprehensive report from the nonpartisan Stimson Center examined U.S. drone policy since Sept. 11, 2001, and found that the steady rise in the frequency of drone strikes during former President Barack Obama’s tenure has continued since Mr. Trump came to power. During his eight years in office, Mr. Obama authorized roughly 550 drone strikes in Pakistan, Yemen, Somalia, and other nations in which the U.S. wasn’t explicitly at war.

In just his first 12 months, Mr. Trump green-lighted at least 80 strikes in those countries and “is on pace to surpass the strike tempo of both of his predecessors, which perhaps signals a great willingness to use lethal force,” the survey says.

The figures do not include military action in countries such as Iraq and Afghanistan, where the U.S. has has a formal military presence for more than a decade, and the strikes in countries such as Yemen and Somalia are typically overseen by the CIA, not the Pentagon.

Analysts argue that one reason for the uptick in the use of drones could be the Trump administration’s relaxation of the rules governing drone strikes. The administration reportedly has lessened the certainty required about a target’s whereabouts before launching a drone strike, and has declared parts of Yemen and Somalia to be area of “active hostilities,” which allow greater flexibility in the use of drones.

But the details of those and other drone policies remain secret, and some analysts contend that whatever progress on drone transparency had been made during the Obama administration has been swiftly reversed.

“The Trump administration appears to be rolling back initial, albeit limited, efforts to increase transparency in the U.S. drone program, which impedes the ability of the public to assess whether the use of drones is appropriate and responsible and to hold the government accountable for any mistakes or wrongful killings resulting from the use of drones in lethal operations,” wrote Rachel Stohl, managing director at Stimson who oversaw the drone study. “A lack of transparency also undermines the legitimacy of the U.S. drone program and the policy underpinning it, and implies that the United States has something to hide.”

A host of other groups, such as the ACLU, Amnesty International, and others, earlier this year released a joint statement calling on the Trump administration to make public much more information about the extent of its drone program, the rules of engagement it is using, and a host of other information.