WASHINGTON — Lawmakers on Thursday questioned President Barack Obama’s push to release more detainees from the Guantanamo Bay detention facility, given the recent disappearance of a detainee transferred to Uruguay and that Americans were killed by released detainees who returned to the battlefield.

Paul Lewis, a Defense Department special envoy for the closure of the Guantanamo Bay detention facility, told the House Committee on Foreign Affairs that the Obama administration now estimates 14 released detainees had returned to Afghanistan and were responsible for the deaths of Americans.

Lewis did not provide details on which Americans died from the attacks. But he said all of the former detainees implicated in the killings had been released during President George W. Bush’s administration.

“We’ve got a lot of dead Americans as a result of this catch-and-release program,” said Rep. Brad Sherman, D-Calif., who is a member of the Foreign Affairs Committee.

The Washington Post has reported six Americans have been killed by former Guantanamo detainees since their release.

At its peak, Guantanamo housed 779 detainees. There are 79 now. Most of the detainees were released under the Bush administration. Obama has released 159 detainees and has worked to close the detention facility permanently since he took office.

Of the 79 remaining prisoners, 29 have been cleared for transfer. The other 50 detainees at Guantanamo could still face judicial punishment, Lewis said.

Last month, a detainee transferred under Obama’s administration, Syrian Jihad Ahmed Diyab, disappeared from Uruguay after potentially violating a travel ban that was part of the terms of his release.

“The fact is that the standard is not elimination of risk, it is mitigation of risk,” said Lee Wolosky, a State Department special envoy for the closure of Guantanamo Bay who testified Thursday before the House committee.

Based on intelligence committee assessments, no Americans have been killed as a result of any of the detainees released since Obama took office in 2009, Lewis said.

In the 2016 National Defense Authorization Act, Congress prohibited the White House from using any funding to close Guantanamo and opposes the transfer of the remaining prisoners who are deemed too dangerous to release.

Closure of the Guantanamo facility is one of Obama’s remaining campaign promises.

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