In his 1961 inaugural address, John Kennedy called the United Nations one of the most important pillars of American security. He devoted an entire paragraph to the organization, saying: “To that world assembly of sovereign states, the United Nations, our last best hope in an age where the instruments of war have far outpaced the instruments of peace, we renew our pledge of support—to prevent it from becoming merely a forum for invective—to strengthen its shield of the new and the weak–and to enlarge the area in which its writ may run.”

No president since then has ever mentioned the UN again in an inaugural address. Last month President Obama proved to be no different in his remarks. He did not cite the organization in that  inaugural nor, for that matter, did he touch on it in his first. Speaking of the UN has become a “no-no” for presidents. This is an especially notable problem given the fact that the UN has been deeply engaged in ongoing crises in Syria, North Korea, Mali and other global hot spots at the direct behest of the UN Security Council, of which the United States is the most powerful member.

What makes this doubly regrettable is that the body, through the years, has become one of the most abused international organizations in the United States—subject to a constant barrage of criticism in Congress and shadowed by the perpetual threats of U.S. dues cut-offs. This means that only an assertive president, using symbolic events like an Inaugural Address, can begin to blunt the impact of such assaults.

Both American political parties are, in part, responsible for the UN's low standing. One can understand why Republican leaders have shown little regard for the UN. After all, they resent any foreign intrusion on American sovereignty and also, frankly, they are happy to use the UN as a cudgel against the Democrats. As for Democrats, there is less of a reason. It was their party which invented the organization in the administrations of Presidents Roosevelt and Truman, helping to organize, finance and host the special conference in 1945 in San Francisco that drafted the Charter.

Mr. Obama's failure to speak of the UN in his 2012 address was hence hardly unusual. Nonetheless it was a particularly surprising omission because his inaugural text is one of the most enlightened of the postwar era. Obama highlighted the progressive canon in all of its magnificence, from women's rights to gay marriage to civil rights to gun control to global warming to financial regulation to Social Security to Medicare—but said nothing about the assembly at Turtle Bay.

Democrats have offered differing excuses for ignoring the UN. Some insist that the body, after 68 years in existence, is so much a part of the geopolitical landscape that no president has to single it out. But the real reason, Democrats privately concede, is that they fear exactly what the Republicans say they will do—vilify Democrats for “weakness” in suggesting that an international assemblage like the UN can play any role in or have any influence over American foreign policy.

Democrats began their retreat from the UN during the Reagan Administration when the UN's General Assembly adopted the “zionism is racism” resolution—a move that infuriated Congress and led to Washington's decision to cut funding to the body. The UN later repudiated that declaration, but since then Democrats have publicly barely defended the organization.

What remains curious about America's relations with the UN over the years, though, is that every president, Republican or Democratic, has, sotto voce, used it to advance U.S. security interests and gain legitimacy for overseas activities. During his tenure, Obama, in particular, has been more active than any of his predecessors at the UN on matters ranging from nuclear disarmament to the Human Rights Council to small arms treaty to sanctions on Iran and North Korea to quasi-intervention in Libya and to various condemnations of state-inspired mayhem.

The UN continues to exasperate the United States from time to time. Washington, for example, is upset over the UN's current investigation into the U.S. drone policy and its vote to give the Palestineans non-member observer status. The UN, of course, on occasion, has also mismanaged its budget, failed to control its peacekeeping troops, tolerated some nepotism and enacted foolish resolutions. But still it plays an invaluable role in enforcing decrees on rogue states and settling conflicts, whether in Mozambique, El Salvador, Guatemala, Cambodia, or Cyprus— all of which relieve Washington from having to devote its own resources to those crises.

If the UN can retain any support in the United States, it requires an American spokesman to spell out why it remains important for our national interests. Only a president using his White House pulpit can draw sufficient attention to the UN's critical role among the public to counteract those who seek to undermine the organization. President Kennedy understood that in his 1961 inaugural address. Will future presidents heed his example?