The United States has been in Afghanistan for more than nine years. Canada and the rest of the NATO allies have been in that friendless, fractured land for nearly as long. And now, as the Harper government unveils plans to keep a contingent of military trainers in Afghanistan until 2014, some Canadians are asking, “Why are we even in Afghanistan?”

The answer is not that complicated, although it has been largely overlooked in Canada and elsewhere.

The heart and soul of the North Atlantic Treaty, which created NATO in 1949, is Article V, the alliance’s collective defence clause. Article V declares that “an armed attack against one or more of them in Europe or North America shall be considered an attack against them all” and obliges members to come to the aid of an attacked ally “to restore and maintain the security of the North Atlantic area.”

Only once in its history has NATO invoked Article V. That was on September 12, 2001. A day earlier, shock troops from al Qaeda, operating from spawning and training grounds in Afghanistan, launched a devastating armed attack against a NATO member. They struck America’s military headquarters, crippled America’s financial centre and killed thousands of civilians.

To be sure, what followed was the very opposite of what NATO’s founders had envisioned. Instead of the United States coming to Europe’s defence, Europe came to help the United States. Immediately after the 9/11 attacks, 13 NATO members deployed radar aircraft to monitor America’s skies.

Canada, of course, was the first NATO ally to stand with America after the attacks. After all, Canadian personnel at NORAD in Colorado and the Northeast Air Defense Sector in New York were standing with their American counterparts during the attacks.

Although America’s very closest allies assisted in the early phases of the war in Afghanistan, it wasn’t until 2003 that Washington enlisted NATO to take control of the UN-authorized International Security Assistance Force (commonly known as ISAF).

And that’s why NATO is in Afghanistan today. We can debate whether the war has been wisely prosecuted, whether the costs are worth the ends and even whether NATO should have invoked Article V in the first place. But if the NATO alliance means anything—if being a member of this consensus-based partnership of 28 sovereign democracies means anything—then individual members cannot quit on the mission in Afghanistan.

The disappointing reality, of course, is that some NATO members never gave the mission much of a chance. Although all of NATO’s members technically have troops in Afghanistan, several are token contingents—some in the single digits—that serve no military purpose. It’s sad and a bit embarrassing that non-NATO members Australia, Georgia and Sweden have more troops deployed than Belgium, Iceland, Luxembourg, the Netherlands, Norway and Portugal—all founding members of the alliance.

Yet that’s not the only indication that some NATO allies don’t take Article V seriously. It pays to recall that NATO’s political leaders and military commanders routinely have to beg for more troops to support the mission in Afghanistan. In 2006, alliance members contributed only 85 per cent of the forces pledged. In 2007, Canada threatened to withdraw its forces if other NATO members didn’t come up with more troops to help. And today, NATO’s effort to build an Afghan security force is in jeopardy because the alliance is a thousand trainers short.

Just as bad, some members don’t allow the troops that are deployed to engage the enemy.  It’s difficult to believe, but throughout the war certain allies have invoked what NATO euphemistically calls “caveats” that strike at the very heart of the alliance’s effectiveness and cohesiveness:

• Reuters reports that caveats have been used by Germany, Italy and Spain to steer clear of Afghanistan’s restive south. Others have played the caveat card to block deployment of personnel near the border with Pakistan.
• Denmark recently refused a NATO request for additional F-16s.
• Perhaps more troubling, Italy doesn’t even permit its fighter-bombers in Afghanistan to carry bombs.
• German forces, until recently, were required to shout warnings to enemy forces—in three languages—before opening fire.

All of this has served to validate Washington’s initial wariness about involving NATO in Afghanistan. The U.S. kept NATO at arms length at the outset of the war, largely because waging war by committee proved so difficult during the 1999 Kosovo campaign, which saw Greece and Italy call for bombing pauses, Germany publicly reject Britain’s suggestion of a ground attack, France veto sensitive targets, and a British general openly disobey the American commander’s deployment orders.

Consequently, as a NATO publication observed in 2002, “The United States did not have sufficient confidence in the alliance to give it a major role” in Afghanistan. This left some in Europe to conclude that Washington didn’t take Article V seriously. More than eight years later, the feeling’s mutual.

Being a member of NATO comes with certain responsibilities. The main responsibility of every member is to come to the defence of another who has been attacked. That’s what the alliance, at its core, is all about. That’s what Article V is all about. And that’s what the war in Afghanistan is all about.