John Kerry entered the political scene in 1971 when he asked Vietnam War policy-makers the obvious question: "How do you ask a man to be the last man to die in Vietnam? How do you ask a man to be the last man to die for a mistake?"

Today, American policy-makers get to ask a very different question about Syria: How do you not ask a drone or cruise missile to stop mass murder?

In life and politics, some people want to do something, and some people want to be somebody. In domestic policy, President Barack Obama wants to do things, lots of things. From the gradual government takeover of health care to education reform to the beginning of the end of the war on drugs to same-sex marriage, the president imposes his agenda. That Barack Obama understands that a presidency is a terrible thing to waste.

Yet on foreign policy, Obama has no vision beyond a slow motion pullout from foreign commitments. From his world view, that makes sense. To have a foreign policy, one must have a vision of what to achieve in the world and believe your nation has something to contribute to that world.

As Andrew Preston shows in his award-winning history, "Sword of the Spirit, Shield of Faith," Americans past saw their nation and its foreign policy as realizing a divine imperative to lead the world. This sometimes went too far. As a prelude to Vietnam, President John F. Kennedy wanted Americans to "pay any price, bear any burden … to assure the survival and success of liberty." And, of course, we know all too well the morally justifiable but horrendously planned invasion and occupation of Iraq. Still, American values were essential to our facing down Nazism and communism, the twin scourges that murdered more than 100 million. Two generations of Americans paid taxes and risked lives for those half-century crusades, which really did save the world.

Obama sometimes nods in this direction. Addressing Assad's chemical weapons, the president said in his Sept. 10 speech, "When with modest effort and risk we can stop children from being gassed to death and thereby make our own children safer over the long run, I believe we should act. That's what makes America different; that's what makes us exceptional."

Unfortunately that argument contradicts years of Obama's writings, statements and foreign policy, encapsulated in 2009 when he declared: "I believe in American exceptionalism, just as I suspect that the Brits believe in British exceptionalism and the Greeks believe in Greek exceptionalism." Seemingly, Washington is no more consequential a world city than Athens. If you think this was taken out of context, read Obama's wonderful autobiography, "Dreams from My Father," written before his national ambitions. Unlike some on the left, Obama basically likes America - he just does not see America as worthy to lead the world.

Few doubt that a few weeks of American cruise missiles and drones would turn the tide of the Syrian civil war without any boots on the ground, forcing Assad to offer serious concessions and knock off the chemical weapons.

Alas, despite two years of advance warning, Obama is ideologically unable to honor our commitment to stop the use of chemical weapons against civilians. Obama will talk, but not act. Assad stays in power, and other dictators have a roadmap for how to face down the superpower.

The nation that used to bear any burden will no longer risk cruise missiles to protect innocent civilians, even children. Our enemies and allies alike understand what this means: American foreign policy is over. What no one knows is what comes next.

Robert Maranto is the 21st century chair in leadership in the Department of Education Reform at the University of Arkansas. Email: rmaranto@uark.edu.