”When we saw Osama bin Laden carry out that bombing attack in Africa, we sent a very strong message by going after his colleagues, and himself, hopefully, in Afghanistan. We weren’t (able) . . . to hit as many terrorists as we wanted, but we sent a message.” So said Defense Secretary William S. Cohen on Oct. 13, to U.S. troops in Saudi Arabia, with regard to the Aug. 20 cruise missile attack on terrorist camps at Khost, Afghanistan.

As James Risen of The New York Times deduced from this and other evidence: ”One of the clear but unstated objectives of last August’s raid on Afghanistan was to kill Osama bin Laden and as many of his lieutenants as possible . . .”

Meanwhile, President Clinton vowed on Nov. 15 to ”intensify” U.S. efforts to help Iraqi rebels bring about ”a new government” in Baghdad–a consummation most unlikely to occur except over Saddam Hussein’s dead body.

Such statements come a bit closer than ever before to official acknowledgment that the United States has tried to kill a foreign leader for acts of war against this country. This has some in Congress and others wondering whether the 1976 presidential order that bars ”assassination” has become–or should become–inoperative.

The answer is no. But the questions are likely to persist, given that the simultaneous spread of terrorism and of weapons of mass destruction poses an ever-growing danger, one severe enough to sometimes justify the pre-emptive killing of terrorists overseas.

One reason for the current confusion is that the deliberately (and usefully) vague assassination ban has never been as broad or as legally binding as is widely supposed. It has never meant that the United States will not use lethal force in response to attacks by foreign enemies.

Nor has it meant that individual enemy leaders responsible for such attacks will never be targeted–although some U.S. officials have pretended it does. Defense Secretary Dick Cheney sacked a general in 1990 for speaking of plans to ”decapitate” Iraq’s leadership by killing Saddam Hussein. ”We never talk about the targeting of specific individuals who are officials of other governments,” Cheney said.

The assassination ban was adopted in 1976, by President Ford, after the public disclosure in 1975 of the CIA’s botched assassination attempts on Fidel Castro of Cuba, Patrice Lumumba of the Congo, and others during the 1960s. These violated international law: None of the targets had been caught sponsoring violence against the United States or its citizens.

As renewed by President Reagan in 1981, in Executive Order 12333, the ban states: ”No person employed by or acting on behalf of the United States shall engage in, or conspire to engage in, assassination.” This committed the United States to heeding international law, reclaimed the moral high ground in world opinion, and signaled U.S. agents to avoid actions that could be considered ”assassination” without presidential approval.

But the assassination ban was never adopted by Congress; it is not enforceable by criminal or other prescribed penalties; it can be revoked–or even secretly suspended–by any president at any time; and it is ambiguous about when the use of lethal force constitutes ”assassination.” $ ?Some champion a broad reading that forbids as ”immoral” the targeting of even a proven killer of Americans, as The Dallas Morning News editorialized on Nov. 3.

Morality has very little to do with it, however, when we’re dealing with acts of war against the United States by enemies abroad, including terrorists. Killing an Adolf Hitler to save millions of innocent lives is the most moral option.

Saddam Hussein is not Hitler. But he took power by assassination, kept it by murder, left a million dead in a war of aggression against Iran, gassed the Kurds, invaded Kuwait, bombed Israeli civilians, tortures prisoners, and threatens chemical and biological warfare. What would be immoral about killing him before he can acquire the weapons to kill thousands more, perhaps in American cities?

And assuming that the administration’s evidence implicating bin Laden in the murder of Americans is solid and that he cannot be captured and brought to trial, what would be immoral about killing him before he can bomb more U.S. embassies?

As a legal matter, the prohibitions of murder in all civilized legal systems have long had exceptions for killing in self-defense. The United Nations charter, which outlawed wars of aggression, recognized that nations possess an ”inherent right of individual or collective self-defense if an armed attack occurs.” There was a solid basis in international law–if not in world opinion–for the targeting of Saddam Hussein in U.S. bombing raids carried out during the 1991 Gulf War.

The legal questions get trickier outside the context of conventional, cross-border wars of aggression. In April 1986, for example, when the United States tried to kill Libyan dictator Muammar Gaddafi by bombing the military barracks in which he and his family lived, the bombs missed him but killed others, including his 18-month-old adopted daughter.

The targeting of Gaddafi was arguably justified as ”self-defense” against his terrorist attacks on Americans. But President Reagan nonetheless insisted at the time that ”we weren’t . . . dropping those tons of bombs hoping to blow him up,” while adding that ”I don’t think any of us would have shed tears if that had happened.”

Reagan seemed implicitly to embrace the perverse principle that it would be wrong to take a clean shot at a mass killer but OK to blow up his house with him and a bunch of innocent bystanders in it.

Why not just admit that we were after Gaddafi and Saddam Hussein? One reason was to deflect domestic and international criticism. Another was fear of retaliation: U.S. leaders would become prime targets themselves if they appeared to be legitimating the killing of individual enemies abroad as a tool of policy.

Clinton administration officials have, nonetheless, been more open about their hope of killing bin Laden than Reagan was about Gaddafi. David Leavy, a National Security Council spokesman, says that White House lawyers had prepared an opinion blessing the targeting of bin Laden as legal under both the U.N. charter and a 1996 anti-terrorism statute authorizing overt and covert military action against terrorist groups.

Leavy told The New York Times that terrorist groups’ ”infrastructure” and ”command and control” are justifiable targets; that such ”infrastructure” is often ”human”; and that the Aug. 20 missile attack was legally designed ”to disrupt the training, organization and infrastructure of the bin Laden terrorist network.” Connect the dots and you have something close to: We were trying to kill bin Laden.

This cautious candor is far preferable to the bad old alternative of deceiving the American people. It may also help prepare public opinion for the possibility of more such missions.

There surely are ever-graver terrorist threats. On top of the dangers of conventional terrorism, foreign enemies–including both heads of state, such as Saddam Hussein, and free-lancers, such as bin Laden–may soon have the means to rain death and destruction down on the United States itself on a scale never before imagined.

It could be done by sending a nuclear truck bomb to Washington or New York or Los Angeles, or more quietly, with germs or poison gas. The Soviet Union was deterred by the certainty of massive retaliation. Terrorists might hope to escape detection, and some might welcome ”martyrdom.”

The hard question is to what extent the mushrooming dangers warrant more-drastic countermeasures. It’s one thing to aim missiles or guns at terrorists based on proof that they are planning to kill Americans; it’s another to do so based on possibly mistaken suspicions that they may threaten Americans, or others. It’s one thing to kill accused terrorists who could not be captured and tried; it’s another to use missiles (or snipers) to shortcut a cumbersome extradition process. And it would be a grave mistake to lose the self-defense justification by drifting back toward targeting foreign leaders–however unfriendly–who have not engaged in or threatened violence against us.

At best, there are obvious risks here–not only that resort to lethal force will provoke more attempts on the lives of U.S. leaders but also that it may inspire several new terrorists to replace every one we kill. And the U.S. track record of bungling in such matters is sobering.

But the message to the world’s terrorists should be unmistakable: If you kill Americans, you will have nowhere to hide. If we can’t arrest you, we will hunt you down and kill you. If you seek weapons of mass destruction, you will be in danger.

Gaddafi, for one, may have gotten the message. He’s still there. But he hasn’t blown up any airliners lately.