Washington — Democratic Senator Chris Murphy of Connecticut warned Sunday that the killing of Qassem Soleimani, the head of Iran's powerful Quds Force, could open a "Pandora's box" that endangers the lives of U.S. officials.

"We do not generally execute high-level political figures of sovereign nations, in part because we know that that opens a Pandora's box that may expose American officials to assassination, but also because we know that ultimately that might get more Americans killed, as it likely will in this," Murphy said in an interview with "Face the Nation."

Soleimani was killed in a drone strike early Friday in Baghdad that was authorized by President Trump, inflaming tensions between the United States and Iran. Top administration officials have said the president's decision to order the strike was in response to "imminent" threats to U.S. diplomats and military personnel, though the details of those threats are unclear.

While Republicans have cheered Mr. Trump's decision as necessary to protect American lives, Democrats are questioning whether the president had the authority to use lethal force against Soleimani or if he should have sought congressional authorization.

The White House sent Congress a formal notification of the strike Saturday as required under the War Powers Act, but the document was classified.

Murphy said he did not believe the Trump administration consulted with Congress before the strike and called it the "intentional execution of a high-level official in a sovereign nation."

"Qassem Soleimani is an evil man. He has absolutely ordered the murder of hundreds of Americans. But he is a high-level representative of a foreign government, a foreign government with a military that could strike at American civilians and American service people," the Connecticut Democrat said. "The question is, why didn't the administration look at other means to try to stop this attack from happening?"

Murphy said Mr. Trump now "has the burden" of telling the American people and Congress why the strike targeting Soleimani was needed to prevent future attacks against the U.S., which he said would justify acting unilaterally.

"The contention here is that by assassinating a high-level Iranian official, that you are actually going to inspire and create more attacks against the United States, not actually prevent those attacks," he said.

While the details of the threats that led to Friday's drone strike have not been released, Secretary of State Mike Pompeo said earlier on "Face the Nation" that the Trump administration would "do our best" to provide information to the public.

Members of Congress, Pompeo added, would be able to see those details when they return to Washington this week.