The conundrums associated with being the world’s sole superpower have been on vivid display over the past two weeks. By launching a war of choice against Libya, President Barack Obama perpetuates the unrealistic expectation that U.S. troops will be deployed on missions that have no plausible connection to national security interests.

In his speech Monday, intended to clean up some of the muddled messages surrounding the Libya action, Obama conceded, “America cannot use our military wherever repression occurs.”

He assured Americans that the operation did not set a precedent for future humanitarian crises. He emphasized repeatedly that the mission is not open-ended.

In another country, such assurances would most likely calm the public’s concerns. But, Obama continued, “the United States of America is different. … To brush aside America’s responsibility as a leader and — more profoundly — our responsibilities to our fellow human beings,” he said, “would have been a betrayal of who we are.”

This line of argument is favored by many of Obama’s foreign policy advisers as well.

“Not acting is acting if you’re the United States,” said Princeton’s Anne-Marie Slaughter, the former director of policy planning in the State Department. “It would have simply been criminal to sit back.”

Another adviser, Samantha Power, won a Pulitzer for her book A Problem From Hell: America in the Age of Genocide and speaks often of the world’s responsibility to protect innocents from harm.

What Obama, Slaughter and Power see as a clear moral imperative and an unadulterated good is, in fact, deeply problematic.

It is a particular challenge for the U.S. Washington is often pressed to use its military to help others in distress. That does not mean the U.S. always sends troops when called. Some places where U.S. troops did not go — for example, Rwanda, Congo and Burma — are as well-known as those where they did.

But this selective pattern of intervention reveals that each decision to send troops abroad reflects a choice based not on a calculation of national interest but, rather, on a far more subjective standard that immediately gives way to charges of hypocrisy and double standards.

Advocates of U.S. military intervention explicitly invoke this form of argument to shame policymakers into action. When she called on the Bush administration to launch military operations in Sudan in 2006, Susan Rice and two co-authors asked “We saved Europeans. Why not Africans?”

Rice, of course, is now Obama’s ambassador to the United Nations and has reportedly played a key role in this Libya decision.

But Rice and others confuse the ability to act militarily with the ability to achieve our stated goals. Many of the world’s problems cannot be solved by military force. Look no further than Iraq and Afghanistan. Military forces are ill-suited to foster the spread of liberal democracy and economic development.

Meanwhile, even if an intervention succeeds in killing, or otherwise disabling, the bad guys in Libya without harming innocents, a U.S. decision to intervene almost always involves us in civil and ethnic conflicts that we don’t completely understand and from which it is difficult to extract ourselves.

Today, for example, we still don’t know much about the Libyan rebels on whose behalf we are fighting and who are reportedly being helped by CIA teams.

Some people might say that such considerations should not prevent us from intervening. When we see that a great wrong is being perpetrated, Obama said on Monday, and we believe that we possess the power and resources to right that wrong, we must act regardless of the risks associated with doing so. But most cases are not so clear cut. And the Libyan case surely is not.

When the U.S. military is assigned a mission intended to serve national security, the right to intervene inheres in the U.S.‘s responsibility to defend this country, our people and our way of life. But Washington has adopted too loose a definition of national interest.

Policymakers and pundits assume the U.S. is so dominant, our military so powerful and our technology so superior, that we can handle multiple missions simultaneously — and that such interventions won’t undermine U.S. security.

But this is a dangerous delusion. By launching the Libyan intervention without a clearly articulated national security interest at stake, without a clear military mission and a clear exit strategy — and without the full support of the American people — Obama has compounded our power problem.