Does the NATO Treaty require the US to go to war?

This pair of commentaries highlight the question of whether the United States is obligated to go to war if a NATO member is somehow attacked:

• Ilya Somin, Using Article 5 of the North Atlantic Treaty to legalize the war against ISIS Washington Post 11/15/2015
• Julian Ku, Should the U.S. Even Bother to Invoke Article V of the North Atlantic Treaty After Paris? Opinio Juris 11/16/2015

One of more reckless bipartisan foreign policy assumptions of the last quarter-century was the eastern expansion of NATO, done without much thought of the risks and potential disadvantages.

Russia has been pushing back over the last eight years in Georgia and Ukraine, the latter in significant part a response to questionable "regime change" manuevers by the US and NATO there.

So if some Trump-type government takes over in, say, Estonia, and decides to stage some military provocation against Russia, does that mean the United States is obliged to restage Napolean's march on Moscow?

Article 5 of the North Atlantic Treaty says:

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

Any such armed attack and all measures taken as a result thereof shall immediately be reported to the Security Council. Such measures shall be terminated when the Security Council has taken the measures necessary to restore and maintain international peace and security. [my emphasis]

But Article 11 (mistakenly referred to as Article IX in the Ko column) also says, "This Treaty shall be ratified and its provisions carried out by the Parties in accordance with their respective constitutional processes." (my emphasis)

Ko plausibly reads this as meaning that the NATO Treaty does not in any way override the US Constitutional provisions on war powers. Not that Congress has been much of a restraint on Presidential warmaking since, well, decades and decades.

But the obligation to go to war under the NATO Treaty is not automatic. Given the current contortions of NATO policy in the Middle East, Turkey's current differences with NATO members since the coup attempt of July 15, and various kinds of mischief-making around Ukraine and the Baltic states, this is probably something worth remembering.