When it comes to national security, Michael V. Hayden is no shrinking violet. As CIA director, he ran the Bush administration’s program of warrantless wiretaps against suspected terrorists.

But the retired air force general admits to being a little squeamish about the Obama administration’s expanding use of pilotless drones to kill suspected terrorists around the world — including, occasionally, U.S. citizens.

“Right now, there isn’t a government on the planet that agrees with our legal rationale for these operations, except for Afghanistan and maybe Israel,” Hayden told me recently.

As an example of the problem, he cites the example of Anwar Awlaki, the New Mexico-born member of al-Qaida who was killed by a U.S. drone in Yemen last September. “We needed a court order to eavesdrop on him,” Hayden notes, “but we didn’t need a court order to kill him. Isn’t that something?”

Hayden isn’t the only one who has qualms about the “targeted killing” program. The chairman of the Senate Intelligence Committee, Sen. Dianne Feinstein, D-Calif., has been pressing the administration to explain its rules for months.

In a written statement, Feinstein said she thinks Awlaki was “a lawful target” but added that she still thinks the administration should explain its reasoning more openly “to maintain public support of secret operations.”

As Hayden puts it: “This program rests on the personal legitimacy of the president, and that’s dangerous.”

There has been remarkably little public debate about the drone strikes, which have killed at least 1,300 people in Pakistan alone since President Barack Obama came to office. Little debate inside the United States, that is. But overseas, the operations have prompted increasing opposition and could turn into a foreign policy headache.

It’s odd that the Obama administration, which came into office promising to be more open and more attentive to civil liberties than the previous one, has been so reluctant to explain its policies in this area.

Obama and his aides have refused to answer questions about drone strikes because they are part of a covert program, yet they have repeatedly taken credit for their victories in public.

After months of negotiations, Atty. Gen. Eric H. Holder Jr. won approval from the White House to spell out some of the administration’s legal thinking in the Awlaki case. But his statement, originally promised for last month, has been delayed by continued internal wrangling.

When it is issued, officials said, the statement is likely to add a few details to the bare-bones rationale the administration has offered in a handful of public statements and court proceedings. The administration has said that strikes against suspected terrorists are justified for two reasons: First, that al-Qaida is at war with the United States, which makes any participant in al-Qaida operations an enemy combatant; and second, that anyone directly involved in terrorist plots against Americans poses an “imminent danger” to U.S. security.

Holder may also shed light on an issue that has been less clear: Should a terrorist suspect who is a U.S. citizen get special treatment? Some in the intelligence community argue that the answer is no — that a U.S.-born member of al-Qaida is no different from an American who joined, say, the German army in World War II. But civil libertarians argue that in a murky war against terrorism, an American such as Awlaki deserves some kind of due process before his name goes on the CIA’s “kill list.”

In fact, officials say, Awlaki did get more due process than most al-Qaida suspects on the list.

They say the administration made a point of naming Awlaki publicly as an al-Qaida leader — putting him on notice, in effect — before he was killed.

And they say the Justice Department held that Awlaki could be killed only if it was not feasible to capture him.

The administration has refused to release that legal opinion, in part because it’s not sure it wants those standards to turn into a binding precedent for later cases.

But there are questions that go beyond the legal underpinning for targeted killing. Who puts names on the “kill list,” and who reviews them? And is the process rigorous enough to withstand outside scrutiny?

In the case of a U.S. citizen such as Awlaki, Obama makes the final call. Or so said Defense Secretary Leon Panetta, who offered a rare bit of on-the-record clarity in an interview with CBS’ “60 Minutes” last week. “In the end, when it comes to going after someone like that, the president of the United States has to sign off,” Panetta said.

There’s also scrutiny from Congress. “There is no intelligence activity the (Senate) Intelligence Committee follows more closely, or conducts more oversight on, than CIA counter-terrorism operations along the Afghan-Pakistan border,” Feinstein said, studiously avoiding the word “drone.”

But congressional oversight comes after the fact, and it is divided between Congress’ intelligence committees, which review CIA operations, and its armed forces committees, which review military operations.

That’s one reason some former officials argue that the administration needs to set up a clearer, more rigorous system of internal review — for its own good. John B. Bellinger III, who served as the State Department’s top lawyer during the Bush administration, believes a good solution would be to expand the jurisdiction of the judges who currently authorize wiretaps to cover targeted killing cases as well.

But most intelligence officials hate that idea. “Why on earth would you want to get a judge involved?” asked one. A better solution, he said, would be appointing a special review office made up of seasoned officials who can’t be fired, to insulate them from bureaucratic pressure.

But that would still invest life-or-death power in a secret corner of the intelligence community, without a clear constitutional foundation.

The biggest problem with this newly invented form of clandestine warfare is that its rules have been made on the fly. The Obama administration, like the Bush administration, has made crucial decisions with little outside review and virtually no public scrutiny.

The administration says it has the authority to kill U.S. citizens who are active in al-Qaida, but it’s never explained how that squares with the Constitution’s guarantee of due process.

It’s past time that it did so.

• McManus is a columnist for The Los Angeles Times.