For all the slick technology, there are grave moral and legal questions going unanswered in the government’s use of armed drones to kill people considered terrorist threats. The problems involving these secretive executions are ably underlined by a bipartisan panel of military and intelligence veterans who warn in a new report that without adequate controls and public accountability, the United States could be on a “slippery slope” into a form of perpetual warfare that invites other nations to follow suit and never explain themselves.

“The United States should not conduct a long-term killing program based on secret rationales,” the panel cautioned in a 77-page analysis released by the Stimson Center, a nonpartisan Washington think tank specializing in international peace and security.

Targeted killings by drones may be justified at times against terrorist threats to the United States, but the “blow back” from unintended civilian killings in places like Pakistan and Yemen is becoming “a potent recruiting tool for terrorist organizations,” the report noted. The panel, which had experienced specialists from the George W. Bush and Clinton administrations, concluded that there was no indication that drone attacks on suspected terrorists had advanced “long-term U.S. security interests.”

The Obama administration should be addressing these issues with regular reports to the public about the rationale for the use of drones and the numbers of militants and civilians killed. Instead, excessive secrecy shrouds these operations. While the report points out that there may be fewer civilian casualties in a drone strike than in a conventional bombing, drone operations need to be subject to credible oversight.