The current Congressional debate over Obama’s request to attack Syria for its use of chemical weapons embodies the same generational consequences and disagreements as the debate over the United States joining the League of Nations did almost one hundred years ago. The outcome of that vote settled the direction of American foreign policy for two decades, the span of a generation. The outcome of today’s debate may well have the same consequences for shaping the role of the United States in the world for another generation.

In 1919, President Woodrow Wilson personally led an ultimately unsuccessful campaign to convince the US Senate to ratify the Versailles Treaty ending World War I, which included the establishment of a League of Nations. Wilson, who firmly believed in compromise and conciliation as the best solution to future disputes between nations, was a member of the Progressive generation, an adaptive archetype similar to today’s seniors, members of the Silent Generation. Wilson told the Senate in July 1919 that "a new role and a new responsibility have come to this great nation that we honor and which we would all wish to lift to yet higher levels of service and achievement". Opposition came from Republican Senators such as William Borah of Idaho, a member of the younger Missionary generation, whose idealist attitudes most resemble today’s Baby Boomers. Wilson’s opponents focused on his idea of a continuing role for the United States in world affairs around Covenant X of the League of Nations, which required all member states to come to the aid of any other member who was a victim of external aggression.  The treaty’s defeat caused the U.S. to assume a relatively passive role in international affairs that didn’t end until the Nazi conquest of much of Europe led President Franklin Delano Roosevelt to propose the Lend Lease Act, which Congress passed in 1941.

Now, another Democratic President has asked another Congress divided along generational lines as well as by partisanship to authorize the continuation of the United States’ role as the world’s policeman that has been the national consensus since World War II. The very first vote on the issue in the Senate’s Foreign Relations Committee revealed the generational split that is likely to continue when the full Senate and House take up the issue. The average age of the seven U.S. Senators voting against the resolution was almost eight years younger than the ten U.S. Senators who voted to authorize the President to use military force. Both members of Generation X on the committee, Senators Marco Rubio (R-FL) and Christopher Murphy (D-CT) cast bipartisan “ no” votes.  The most strident opposition came from GOP Senator Rand Paul of Kentucky, born on the cusp of generational change in 1963. He happily embraced attacks from his older Republican colleagues, who argued that his streak of libertarianism would return the country to the isolationist path it abandoned after the attack on Pearl Harbor.

Unfortunately, none of the members of Congress who will cast final votes on the resolution are members of the nation’s largest and most diverse generation, Millennials. The debate comes too soon for them to be eligible to serve in the Senate, but their attitudes and beliefs are certain to have an impact on the nation’s foreign policy in the longer term. Millennials are more likely to support intervention by the United States on behalf of causes than on disputes between nation-states. For instance, only 12 percent of Millennials express support for the United States intervening to promote democracy, whereas 42 percent support using the U.S. military to halt genocide. They are also more inclined to support efforts when they represent the concerted action of allies, rather than a go-it-alone decision by the United States. By a three-to-one margin, Millennials believe that the United States should take the opinion of other countries into account when making foreign policy decisions, and about one quarter of them don’t believe the country does that frequently enough.

President Obama’s initial reaction to the use of chemical weapons reflected his sensitivity to these generational attitudes. He was spurred into action against Syria because it violated the prohibition on the use of such weapons by the Geneva Accords of 1925--cause enough in his opinion to warrant retaliation by the United States. When  efforts to gain support for such action failed in the United Nations and  in the British House of Commons  the president  decided to turn  to  Congress and seek its approval as a way to build consensus for the strikes.  However in doing so, the administration inevitably had to accommodate arguments that such action was necessary to project our power against rivals such as Iran and in support of allies such as Israel in order to win over support from older members of Congress who tend to see the world through a more traditional, balance-of-power lens.

The push and pull of generational and partisan differences will continue to shape today’s watershed debate over Syria in the Congress. Whether its outcome lasts for decades or is simply another step in an ongoing debate about America’s role in the world in the 21^st century will depend on the degree to which its final resolution resonates with the attitudes and beliefs of the Millennial generation that will ultimately determine the nation’s future.