In Hillary Clinton's farewell remarks in February on stepping down as President Barack Obama's secretary of state, she echoed one of her predecessors, Madeleine Albright, declaring America to be "the indispensable nation."
"We are the force for progress, prosperity and peace," Mrs. Clinton elaborated. "And because we have to get it right for ourselves."
Ms. Albright had put it this way: "If we have to use force, it is because we are America. We are the indispensable nation. We stand tall. We see further into the future."
The phrase has also been uttered by Presidents Bill Clinton and Barack Obama (who used it in a candidates' debate last year against Mitt Romney).
Bill Clinton, speaking in 1996 of the U.S.-backed NATO military involvement in Bosnia, spelled out the idea: "There are times when America, and only America, can make a difference between war and peace, between freedom and repression, between hope and fear. Of course, we can't take on all the world's burdens. We can't become its policeman. But when our interests and values demand it and when we can make a difference, America must act and lead."
The notion has also been raised in our more recent involvements in Afghanistan, Iraq and Libya. In the first of these conflicts, American military action was imperative in response to the 2001 terrorist attacks on the World Trade Center and Pentagon.
But in the others, the situation was not so clear-cut. Despite vowing specifically not to make our military the world's policeman or to engage in nation building, American presidents have undertaken or continued such exercises. Although Barack Obama as a candidate in 2008 vowed to end the wars in Afghanistan and Iraq, and although as president he has taken steps to do so, internal strife grinds on in both places and American forces continue to take casualties. As Syria disintegrates in civil war, many are calling for U.S. involvement there.
In the intervention that ousted Libya's dictator, Mr. Obama provided limited air cover but yielded leadership of the international response to the British and French. It was a significant pivot away from the earlier American roles as policeman and nation builder, as has been his current reluctance to plunge into the morass in Syria.
All this has raised questions about the United States as "the indispensable nation," and about its credibility and leadership in the international community.
In the run-up to the 2003 invasion of Iraq, the specter of alleged weapons of mass destruction in Saddam Hussein's hands won support for the war, though the weapons never were found. This time around, allegations of use of chemical weapons in Syria, charges not yet persuasively established, are being aired to justify American intervention of some sort, at least along the lines of our involvement in Libya.
Mr. Obama, seemingly uncertain in gauging the U.S. interest as well as the wisdom of committing military resources, has already eroded American credibility at home and abroad by talking loosely about "red lines" to be crossed, and "game-changers" triggering an unspecified administration response.
Also, by resurrecting their charges of a cover-up of the administration's incompetence in the attacks on the American consulate in Benghazi, Republicans have at least temporarily rekindled the domestic debate over the credibility of Mr. Obama, and of Hillary Clinton as secretary of state.
More significant, however, is whether the current furor over Syria will finally melt the administration's reluctance to lead or even get seriously engaged in a military way to ameliorate the human suffering there.
Since the Libyan exercise, Mr. Obama has seemed determined to reduce America's role as the world's policeman and nation-builder, after a post-Cold War era of asserting the principle and conduct of being "the indispensable nation." But Syria now confronts him with weighing Bill Clinton's admonition that "when our interests and values demand it and when we can make a difference, America must act and lead."
Jules Witcover is a former longtime writer for the Baltimore Sun. His latest book is "Joe Biden: A Life of Trial and Redemption" (William Morrow). You can respond to this column at firstname.lastname@example.org.