NATO has recently had one of its regular meetings of the "Military Committee" in Victoria, B.C., Canada, with appropriate demonstrations against it for Canada's role within NATO and Afghanistan. Phil Lyons, the organizer of the demonstration, which ended peacefully, says "NATO is now a weapon of American Imperialists." Another demonstrator asks, "I don't understand why NATO exists," then answers his own question, perhaps without realizing it, that "NATO is a war tool the West uses to intimidate other nations into submission." 
They are correct regardless of the high-sounding rhetoric that emanates from the government about international humanitarian rights and the war on terrorism.
NATO as it currently stands has a dual command structure, SACT and SACEUR.
SACT is the acronym for the Supreme Allied Commander Transformation, the transformation being that of making NATO forces into a U.S. styled rapid deployment force anywhere in the world. SACT will be dual-hatted (meaning the same guy has both positions) as Commander, US Joint Forces Command. This one person is U.S. Air Force Gen. Lance L. Smith, who is headquartered in Norfolk Virginia. SACEUR is the acronym for Supreme Allied Command Europe and is be dual-hatted as Commander, US European Command, General John Craddock, United States Army who is appointed by the US President. His headquarters are in Mons, Belgium.
It should be obvious that NATO is led by the U.S. military. With its current role involved with the powers of the American empire in unilateral pre-emptive actions that generally work against international law, yes, NATO is nothing but an extension of that empire, a tool of the corporate-military structure that is part and parcel of the American government.
The Military Committee's role is defined as: "In times of crises, tension or war, and in relation to military operations undertaken by the Alliance such as its role in Bosnia-Herzegovina, Kosovo and Afghanistan, its role is to advise the Council or Defence Planning Committee of the military situation and its implications, and to make recommendations on the use of military force, the implementation of contingency plans and the development of appropriate rules of engagement."
Of course there is little that is defensive about NATO's current role, having used uninvited force in Bosnia-Herzegovina and Kosovo, and while they may have been 'invited' into Afghanistan, it was under an established puppet government led by a compromised Hamid Karzai. The NATO treaty does say that the signatory countries "seek to promote stability and well-being in the North Atlantic area," a definition which is pushed to the extreme with the former Yugoslavia and is absurd with Afghanistan. In addition the NATO treaty indicates "The Parties to this Treaty reaffirm their faith in the purposes and principles of the Charter of the United Nations and their desire to live in peace with all peoples and all governments." 
The UN Charter states in part, "In the event of a conflict between the obligations of the Members of the United Nations under the present Charter and their obligations under any other international agreement, their obligations under the present Charter shall prevail." Therefore any obligations and rules and regulations established under the UN prevail over anything that NATO decides, or at least it is supposed to.
As the UN Charter "prevails over all other treaties...countries cannot exempt themselves from the provisions of the UN Charter, which include...the international rules governing recourse to military force." These international rules have developed over time through various treaties, charters, agreements, and conventions or through customary law involving the wide acceptance of a rule by a clear global majority. International humanitarian intervention in the form of military force is not an accepted concept of international law, and even if it was, cannot over-ride article 2(4) of the Charter that says "Members shall refrain...from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations." It would seem that NATO's "recommendations on the use of military force" and "its development of appropriate rules of engagement" would be completely over-ridden by the UN Charter.
The Afghanistan occupation is not counter to the political independence of the state (recognizing that it is a puppet government established under U.S. auspices and controlling very little of Afghanistan); and it does have Security Council authorization (it fits somehow under the "mandate" of the "International Security Assistance Force" but is not recognized in its own right, an after the fact recognition of its actions): leading to the observation that the presence of Canada's military in Afghanistan is within international law. 
As for self-defence, "Nothing...shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security." This has been done, yet problems still remain under international law and with the 'moral' basis for the war.
Canada's own elected representatives and military leadership promote Canada's military action in Afghanistan to support the U.S. under the pretext of humanitarian intervention. However, "the significance of humanitarian concerns to the international law on the recourse to force remains at the level of political will" and can not "be considered to have acquired legal force." Also, the Canadian government advocates its pro-democratic intervention role, but use of force for that is prohibited under the UN Charter as well.
Canada's role, as an occupying force under international law, contains other concerns along with the above: the treatment of prisoners of war; the destruction of civilian structures (they've built some roads, but what about the farms and houses that have been destroyed?); the 'rendition' or transfer of prisoners to the Afghan forces (this issue came to light recently but was quickly dropped by the media once they were reassured that Canada had access to "its" prisoners); and the care and safety of the occupied population.
NATO's role in Afghanistan, while ostensibly under UN approval, is in reality under U.S. command. Canada and NATO have accepted U.S. command, and are faithfully performing their empirical duties in Afghanistan. While Canadian government rhetoric has been about rebuilding Afghanistan, the reality on the ground is about battling an insurgency, that good or bad, is a native insurgency. Again, while the rhetoric is about rebuilding a democratic Afghanistan, the ultimate purpose of American geopolitical strategy in the region is to control the oil and gas supplies and routes from the Caspian Basin and guard against Russian and Chinese control of the same.
Counter to that, elements within Pakistan are calling for all foreign forces to leave Afghanistan in order that Pakistan can negotiate for peace, following on the success of a recent peace 'jirga'. The Afghan government itself has called for recognition of the Taliban as political players within the Afghani government, as have several domestic U.S. sources. For Canada to continue in its role as occupier and aggressor within Afghanistan is fully counterproductive to both reconstruction and the war on terror.
Reconstruction will not occur within a circle of military battles that can never win the war, and only cause more civilian deaths and recruit more people to the anti-occupation forces. At the same time that the NATO meeting was taking place in Victoria, Canadian troops were fighting in Helmand Province to retake positions they had "taken" previously. If Canada wants a long war, they have certainly found the right environment for one.
Always, apart from the legalities, it is a useless endeavour to invade another country and try to impose one's own version of the 'white man's burden' upon the indigenous population. The reality behind that pretext is a combination of two main forces. The first force is racism - a creation of the 'other' whose life has no value as they do not embrace our own beautific moral standards and self-aggrandizing democracy. The second forces are those of capitalist imperialism, the fullest extension of corporate neoliberalism and its desire for control of resources and labour.
The war on terror will never be won by invading and destroying governments and civilian infrastructures, or by supporting unwanted puppet governments, but by using international investigative forces and international courts - which of course leads to the obvious that if foreign forces would go home, the war on terror would diminish significantly as its antagonizing force would be gone. The arguments for democracy, for making the world a safer place, for protecting Canada, for trying to prevent a civil war, for countering terrorism, for rebuilding Afghanistan, or for honouring those who have already died by not cutting and running, do not stand up to common sense and moral scrutiny any more than they do international legalities.
A true democracy, actually asking the people of the country what they desire and then abiding by their wishes - and not using a contrived idealism of morality and democracy - will go a long way to create a safer, more culturally diverse and healthy and equal world.
Canada should get out of Afghanistan. Canada should get out of NATO. If the countries involved wished to truly be independent actors and thinkers, then NATO itself should be disbanded - it has long outlived its original purpose and is now being used as another force for American empire.
 Byers, Michael. War Law - Understanding International Law and Armed Conflict. Douglas & McIntyre, Vancouver, Canada. 2005. p. 6.
 Personal correspondence, Michael Byers.
 Byers, ibid, p.7
 Byers, ibid, p. 102
 arguments similar to those presented in Anthony Arnove's Iraq - The Logic of Withdrawal. Metropolitan Books, Henry Holt and Company, New York, 2007.