My hunch is that historians will be a lot kinder to President Obama than we are in 2014. We’ve had presidents who have faced major-league crises — think Lincoln in 1861 or FDR as he battled both The Great Depression and the expansion of fascist Germany and Japan. However few presidents have faced so many crises at the same time.

President Obama not only has to balance an expanding economy emerging from recession while controlling interest rates that, should they rise too fast, will plunge us back into recession. He needs to deal with foreign crises in Gaza and in Libya, both of which are on the brink of becoming failed states. He needs to deal with the Iranian nuclear program without starting an un-winnable war, address the conflict in Ukraine, and he faces increasing pressure to contain China as it exerts pressure on its neighbors in Southeast Asia.

Then there is the mess in North Korea, and also the barbaric behavior of a powerful — yes, powerful — Islamic State (ISIS) that advertises its godliness by beheading western reporters and thousands of Muslims who don’t buy into its own brand of Islam.

Not to mention that if the Islamic state continues to expand, it will destabilize the entire middle east.

Finally, there is Syria, still convulsed by civil war, where President Obama said nearly three years ago that the use of poison gas would constitute a "red line." What would happen if Syria’s president, Bashir Assad, crossed that red line? Presumably, the U.S. would militarily support the democratic opposition to Assad.

And yet the U.S. did not act when it became clear that the Syrian government used chemical weapons against its own population in clear violation of international law. We did not send soldiers to punish Assad. We did not meaningfully aid the Syrian opposition.

And so we damn Obama for making empty threats and for his inaction.

Well, it’s easy to criticize, but few of us bother to ask why President Obama refused to aid the democratic opposition to Assad. In one of the better opinion pieces I’ve read in the past year, columnist Thomas Friedman in the New York Times addressed this issue by posing a few good questions:

1. Can anyone reading this op ed name the leader of the Syrian opposition? The answer is "no," and that’s because the moderate opposition to Assad lacks effective leaders.

2. Why have the Israelis sat on their hands during the Syrian civil war? Because they realize that the alternative to the hated Assad is likely to be even worse than Assad.

3. Why have thousands of Islamic jihadi’s from Europe and even from the U.S. joined the bad guys, but not one has joined the democratic opposition?

4. Might Syrian moderates and democrats have defeated their Islamic rivals when the richest oil monarchies like Saudi Arabia and Qatar are funding the fundamentalist radicals in Syria? The answer has two letters, one of which is "n" and the other "o."

5. Knowing that our support for the "moderate" Shi’ite opponents of Saddam Hussein’s Iraq led to a repressive regime much more closely allied to Iran than to the U.S. once we withdrew our troops, why should we believe that the outcome would be different in Syria?

In short, Friedman — and Obama — are right to think that caution is in order. It’s easy to get into wars. It’s a lot more difficult to get out of them. American isolationists like Rand Paul are delusional to think that we can simply walk away from the mideast. Equally delusional are those who think the U.S. can unilaterally reorder the region. There are limits to American power, and Obama understands this better than most of his critics.

Gary Ostrower teaches diplomatic history at Alfred University. He is the author of The United Nations and the United States" (Twayne Publishers).