One bright afternoon in June 1981, Israeli F-16 jets streaked low across the Iraqi desert. Spotting the gleaming domes of the unfinished Osiraq nuclear reactor, the pilots decimated it with bombs - a bold preemptive strike in the name of self-preservation.
The world reaction to the strike was swift and critical, with the United States and the rest of the UN Security Council unanimously condemning it.
But now, two decades later, the Bush administration - warning of time-bomb terrorists and the spread of deadly mass weapons - proposes a far more open-ended, sweeping use of preemptive force than Israel's.
In a controversial expansion of the Bush doctrine - the unilateralist "with us or with the terrorists" foreign policy that followed Sept. 11 - the administration is making a stark argument for striking first.
"Defending against terrorism and other emerging 21st century threats may well require that we take the war to the enemy," Defense Secretary Donald Rumsfeld said last week in a speech at the National Defense University.
In one extreme scenario - one nevertheless under consideration by US officials - the Bush administration could claim the right to overthrow the Iraqi regime of Saddam Hussein preemptively. The goal: to prevent Hussein - alone or through terrorists - from threatening the United States or its allies with weapons of mass destruction (WMD).
"This is absolutely a new wrinkle," says Kurt Campbell, of the International Security Program at the Center for Strategic and International Studies. "There has been no presidential doctrine on terrorism before now."
I contrast, over the past 20 years, American military strikes against terrorist targets have been limited and for the most part retaliatory:
In April 1986, the US struck military sites in Libya in response to the bombing 10 days earlier of a Berlin discotheque frequented by US troops.
In June 1993, in retaliation for Iraq's alleged plot to assassinate former President George Bush in April, US forces fired Tomahawk cruise missiles at the Iraqi intelligence service headquarters in Baghdad.
In August 1998, 13 days after the bombings of the US embassies in Kenya and Tanzania, the US fired cruise missiles at training camps in Afghanistan and a pharmaceutical plant in Sudan suspected of making chemical weapons.
Yet today, many terrorism experts view such "action-reaction" strikes as ineffective.
"We learned by experience that bombing installations and institutions does not work in terms of pressing the regime to do something," says Matthew Levitt, a former FBI counterterrorism expert at the Washington Institute for Near East Policy here.
Two central factors drive the shift toward a preemptive policy against the threat of terrorism and WMD. The first is the realization since Sept. 11 of US vulnerability to thousands of terrorists trained and willing to carry out attacks against Americans.
The other is the recognition that time is evaporating for Washington to act against another, old, long-anticipated threat - chemical, biological, and, most critically, nuclear weapons programs carried out by "rogue" states such as Iraq, Iran, and North Korea.
"Time is not in our favor," the Pentagon official says. "There is a sense of urgency because of the Iraqi program, among others. The Iranian program is moving along in dangerous ways, and this administration has always been nervous about North Korea and whether its nuclear weapons program is completely constrained by the 1994 agreement."
In 1998, a report to Congress by a bipartisan commission led by Mr. Rumsfeld warned that rogue states were seeking to acquire ballistic missiles with nuclear payloads, and the US could face a ballistic missile strike within five years.
Meanwhile, officials say, known links between terrorist groups actively pursuing WMD and states developing them led President Bush to decide that preemptive action is warranted - and indeed, as he said in his State of the Union address last week, the risk of waiting to act "would be catastrophic."
Yet in what appeared to be a broadening of the war beyond terror, President Bush indicated that threat of WMD alone would justify preventative US action. "The United States of America will not permit the world's most dangerous regimes to threaten us with the world's most destructive weapons," he said.
"I think nuclear weapons is what this is all about," says Tom Nichols, a professor at the US Naval War College in Newport, R.I. "This is a fundamentally new problem, because nuclear weapons allow a weak state to inflict a huge amount of damage overnight."
Still, the Bush administration faces an uphill battle in convincing skeptical European and other allies. And the UN charter allows for self-defense in case of an armed attack, legal experts doubt it would sanction a US preemptive move to overthrow Iraq - short of a specific threat by Baghdad. "The rest of the world would by and large consider it illegal, and American lawyers would have a hard time putting together ... a proposition it was right," says Detlev Vagts, a professor of international law at Harvard Law School in Cambridge, Mass.