Legally speaking, the NATO treaty does not require the U.S. to “automatically” use force to defend allies
The New York Times is carrying a story (“Donald Trump Sets Conditions for Defending NATO Allies Against Attack“) reporting that the Republican presidential candidate “explicitly raised new questions about his commitment to automatically defend NATO allies if they are attacked.” Mr. Trump, the Times says, would “first look at their contributions to the alliance” before deciding upon a response.
Without commenting on the wisdom of this position, allow me to answer this question: as a matter of law, does the NATO treaty “automatically” require the U.S. use force to defend a NATO ally? The short answer is “no.”
Here’s what Article 5 to the NATO treaty provides:
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 recognized 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.
The crucial point is that the response to an “armed attack” that a NATO member owes to a NATO ally is simply whatever “it deems necessary.” NATO itself provides an explanation that illustrates that the U.S. has always resisted the notion of an “automatic” obligation:
At the drafting of Article 5 in the late 1940s, there was consensus on the principle of mutual assistance, but fundamental disagreement on the modalities of implementing this commitment. The European participants wanted to ensure that the United States would automatically come to their assistance should one of the signatories come under attack; the United States did not want to make such a pledge and obtained that this be reflected in the wording of Article 5. (Italics added.)
Importantly, Article 5 should not be read in isolation from Article 11 which states that “the Treaty shall be ratified and its provisions carried out by the Parties in accordance with their respective constitutional processes. (Italics added.) Following the Paris terrorist attacks last November, Hofstra’s Professor Julian Ku referenced Article 11’s acknowledgement of the need for countries to adhere to their “respective constitutional processes” and observed this about the relationship of U.S. domestic law to the NATO Treaty:
If you are someone who believes that Congress must authorize the use of force by the President in most cases, [then] this language would mean that the President has to go back to Congress. This might actually happen. Republican presidential candidate Jeb Bush actually called for a “declaration of war on [ISIS]” today. Of course, if you believe (as I do) that the President has independent constitutional authority to use military force without Congress in most circumstances, than all Article XI does not limit the President much.
The key is that the NATO Treaty neither obviates the need to find domestic U.S. legal authority to use force, nor forecloses a decision not to use force at all.
Significantly, Ku has also pointed out elsewhere that most U.S. treaty obligations are similar, that is, they do not, as a matter of law, automatically act as some sort of pre-authorization to use force but rather must also find U.S. domestic law support either in a declaration of war or other statutory authorization, or within the President’s authority under Article II of the Constitution. In discussing (last January) US obligations towards Taiwan Ku said (and I agree) that:
Ultimately, the core of any security guarantee is not legal obligation, but political will. Legally speaking, Taiwan lacks an ironclad U.S. security guarantee against an attack by China, but this is true for just about everyone else as well including NATO. Whether the U.S. will come to the defense of Taiwan, or any other country, is largely contingent on questions of diplomacy, military facts, and political will. (Italics added.)
Interestingly, in March of last year The Economist dismissed the argument made by some Baltic states who feel threatened by Russia “that an attack on them would mean an all-out East-West confrontation thanks to Article 5 [of the NATO Treaty]” by concluding that “Article 5 does not specify such a response.” It said that “[t]he decision to act, or not, would be made not at NATO HQ in Brussels, but in Washington, DC”, adding that as “many eastern NATO members worry, it is hard to imagine an American president risking nuclear war to defend a tiny country half a world away.”
According to the Times, Mr. Trump’s position is based on his concerns about NATO members “taking advantage of what he called an era of American largess that was no longer affordable.”
The U.S. is, by far, the largest contributor to NATO. Indeed, while U.S. defense spending amounts to about 3.6% of GDP, only four other NATO members are meeting NATO’s own guideline of spending 2% of GDP on defense. In 2011 former Secretary of Defense Robert Gates warned NATO that:
The blunt reality is that there will be dwindling appetite and patience in the U.S. Congress — and in the American body politic writ large — to expend increasingly precious funds on behalf of nations that are apparently unwilling to devote the necessary resources or make the necessary changes to be serious and capable partners in their own defense.
Similarly, last April President Obama complained about “free riders,” that is, nations who don’t “carry their weight” in terms of acquiring and maintaining defense capability but who nevertheless expect U.S. security backing. This wasn’t a specific reference to NATO, but would seem to include its members among other allies.
Be that as it may, the U.S. has more legal flexibility as to the use of force than many might assume defense agreements like that of NATO would allow.
Just for the record, I am a registered independent, and as a retired military officer I do not publicly support any candidate