The "war on terror" existed years before the United States invaded Iraq.
Most people just didn't think much about it.
But when US troops, tanks, and attack aircraft began blasting their way from Kuwait toward Baghdad a year ago Friday, it was a watershed mark in what is likely to be the principal form of armed conflict in the 21st century.
In many ways, the battles in Iraq (and those that preceded them and continue in Afghanistan) are the first major test of America's place in this new post-cold-war world - especially of the Bush administration's more muscular policy of preemptive war, with a go-it-alone attitude if necessary.
The largest US war effort since Vietnam already is having a major effect on the US military, including the disposition of forces around the world.
Warfighting doctrine, tactics, weaponry, recruiting and retaining military personnel, the role of women now fighting and dying in combat, an unprecedented use of National Guard and Reserve forces in an active duty role - all are being tested.
The country's diplomatic position vis-à-vis its friends and adversaries also faces major challenges as a result of the year-old Iraq war. For example, will last week's deadly terrorist attack in Spain (along with Britain, Spain has been one of the major US allies in Iraq) arouse European countries to help American peacemaking and nationbuilding efforts in Iraq? Or will it increase public opposition to Mr. Bush's policy there?
More likely the latter, if Spain's weekend election is a clue, and this undoubtedly will impact the US military as well.
The conduct of the war - at least up through the fall of Baghdad - seems to confirm Defense Secretary Donald Rumsfeld's desire to have more lighter, faster-moving combat units able to communicate and coordinate in real time and backed up with long-range, more accurate weapons, and special-operations forces.
"Rumsfeld's notion that you can fight wars with smaller forces I think is for the most part proving out," says Charles Peña, director of defense policy studies at the Cato Institute. "But what you can't do is occupy countries with smaller forces. So all the defense transformation and technology in the world is not going to help you when it comes to having to occupy a country."
Others point out the difference here between Afghanistan and Iraq - the two major US fronts in the war on terrorism.
"Afghanistan suggested that a larger number of smaller ground forces backed with precision munitions, unmanned aerial vehicles, and good communications are the wave of the future for warfighting," says retired Army Col. Dan Smith. "Then came Iraq, in which the older, bigger legacy systems and units predominated, or seemed to until the Iraqis failed to show up for the war."
That the Iraqi Republican Guard and other elite units faded from the battlefield (perhaps re-forming into the hit-and-run groups that have continued to kill allied soldiers as well as Iraqi and foreign civilians) means the true test of the US military has yet to occur, some experts suggest. "We may face similarly inept enemies again in the future, but that isn't what you'd call a good planning assumption," says Loren Thompson, head of security studies at the Lexington Institute in Arlington, Va.
For years, Pentagon officials planned around the "one-and-a-half war" scenario - one major war (in central Europe, for example) and another smaller simultaneous conflict somewhere else in the world.
How big should US forces be?
Now, it appears, Pentagon planners have to worry about how to handle the aftermath of even "half" a war - particularly as it affects the hundreds of thousands of troops rotated in and out of peacekeeping and nationbuilding duty.
And most of the challenge involves the numbers of soldiers, sailors, airmen, and marines that can be counted on.
"Avoiding a personnel crisis in the all-volunteer military has become the chief force management challenge for Secretary Rumsfeld and his successor," says Michael O'Hanlon of the Brookings Institution in Washington, "much more so than transforming the armed forces or relocating overseas bases."
To compensate, Army troops from Germany and marines from Okinawa are being rotated into Iraq.
"Rumsfeld already had tendencies to pull troops out of existing deployments - Europe and maybe even Korea," says defense analyst Ivan Eland of the Independent Institute in Oakland, Calif. "The stretch because of Iraq has likely strengthened those tendencies."
At the same time, reserve components now are scheduled to make up 40 percent of the force in Iraq, Kuwait, and Afghanistan. One reason: Reservists and those in the National Guard are more likely than active duty troops to have had the training necessary for postcombat duty, including as translators, military police, and civil affairs specialists.
While such trends may argue for either increasing the active duty force or decreasing their missions around the world, they may also help Americans reconnect with their military. Ever since the end of the draft in 1973, fewer and fewer Americans have had direct (or even indirect) contact with those in uniform. But with small towns around the country now watching their men and women marching off to war, returning with stories of combat, some of them wounded or not coming back at all, that gap between citizen and soldier has closed dramatically.
"There is a universal, patriotic pride in what they are doing and how well the rank and file do it, perhaps helped by the embedded reporters who made the operations in Iraq very personal," says retired Navy Capt. Larry Seaquist, a former warship commander and Pentagon strategist. "There is a huge, personal connection with the war through Guard and Reserve participation, which seems to touch every town and village; and there is a sense of solidarity generated by the common feeling of vulnerability to terrorist attack."
Still, that could portend trouble for the Pentagon, adds Captain Seaquist: "It could mean that there may be a clash ahead between the citizenry and the high command over what the military does and how they do it. American Main Street values do not comport with a military increasingly formed around super-secret Special Forces or one using high-tech disinformation campaigns in its combat tool kit."
Especially since Vietnam, it's often been observed that military officers are more reluctant to go to war than the elected officials and civilian appointees who set policy. This may become more obvious, especially with the new kind of war in which those in uniform are likely to find themselves.
"Military guys are reluctant dragons," says retired Air Force Col. Sam Gardiner. "They have always been concerned that policymakers fully understand what they are doing before they commit treasure into harm's way."
"I can hear the arguments when policy makers talk of using force: 'Yes sir, we can win quickly, but that is when the problems will start. We could be there for years. Just look at Afghanistan, Iraq, and Haiti,' " Colonel Gardiner says.
In important ways, America's adversaries no doubt have gone to school on the Iraq war as well. In Iraq, that has meant roadside bombs rather than firefights; and when US troops began emphasizing "force protection" to reduce casualties, it's meant attacking Iraqis and foreign-aid workers who support the US-led effort. In other words, what started out as a straightforward battle against an identifiable foe has become unconventional war.
"Unfortunately, there is one other lesson that may be emerging from the insurgency that followed conventional victory," says military analyst Loren Thompson of the Lexington Institute, who supported the US invasion. "America's military is in danger of becoming 'the redcoats' - a readily identifiable and isolated force that numerically inferior adversaries can gradually wear down through a combination of unconventional tactics and patient pressure."
"Time will tell," Dr. Thompson says, "whether America has the resolve to prosecute low-intensity conflicts against persistent adversaries."