People who talk incessantly often talk imprecisely, and President Obama, who is as loquacious as he is impressed with his verbal dexterity, has talked himself into a corner concerning Syria and chemical weapons.

This is condign punishment for his rhetorical carelessness, but the nation's credibility, not just his, will suffer. His policy is better than his description of it, and his description is convoluted because he lacks the courage of his sensible conviction that entanglement in Syria would be unwise.

Nine months ago, Obama said: "We have been very clear to the Assad regime ... that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus." This is less a policy than a large loophole masquerading as a policy.

"Moving around or being utilized" (emphasis added) suggested that moving the weapons would cross the red line. Now, however, the argument is entirely about whether they have been used. How much is "a whole bunch"? Can less than this be utilized without changing his "calculus"? What, if anything, might a changed calculus mean in terms of U.S. actions?

By last week, the "red line" had been demoted to just "another line": "To use potential weapons of mass destruction on civilian populations crosses another line with respect to international norms and international law. ... That is going to be a game-changer." Well.

What about the use against other than civilian populations? Do Bashar Assad's armed enemies count as civilians? How might the game change? Or is the use of such weapons itself the change? Does the line matter only with regard to international law and norms, not to U.S. policy?

Obama, who supposedly speaks so well, is behaving better than he is speaking. In an essay in the May/June issue of the American Interest ("Leading from Behind: Third Time a Charm?"), Owen Harries and Tom Switzer argue that Obama understands the "most important sentence ever written about American foreign policy," Walter Lippmann's formulation: "Without the controlling principle that the nation must maintain its objectives and its power in equilibrium, its purposes within its means and its means equal to its purposes, its commitments related to its resources and its resources adequate to its commitments, it is impossible to think at all about foreign affairs."

An unidentified Obama aide did Obama no favor when he characterized (to the New Yorker) Obama's policy as an oxymoron — "leading from behind." Those who have the courage of Obama's convictions should praise his policy as an escape from the delusional ambition that the United States can and should lead everywhere.

The argument about what, if anything, the United States should do about developments — at once appalling and opaque — in Syria is just the latest flaring of a controversy that can be said to have been kindled in 1990 when Jeane Kirkpatrick urged the United States to resume its life as a "normal nation." Although Kirkpatrick was a Democrat until 1985, she was in accord with Ronald Reagan, for whom she served as U.S. ambassador to the United Nations, regarding foreign policy. In an article written after the Berlin Wall fell and before Iraq invaded Kuwait and the United States prepared to reverse this aggression, Kirkpatrick wrote: "With a return to 'normal' times, we can again become a normal nation. ... It is time to give up the dubious benefits of superpower status."

One of those benefits is that those who make U.S. foreign policy can scrub from their vocabularies the word "unacceptable," which usually denotes something America actually must accept. Or even already is accepting, as when (March 11) Tom Donilon, Obama's national security adviser, strangely said "the United States will not accept North Korea as a nuclear state."

In December, Obama said: "The use of chemical weapons is and would be totally unacceptable." Not partially but totally, so ...

Remember Colin Powell's U.N. speech detailing Iraq's weapons of mass destruction, a speech the accusations in which Powell meticulously vetted during days he spent at CIA headquarters? Obama is muddled about his own red lines but he is rightly cautious about what it is possible to know about the Assad regime's behavior.

Then-Secretary of State Hillary Clinton said "it is in our DNA" to believe "there are no limits on what is possible or what can be achieved." Obama seems to know better. Certainly his confused — or perhaps calculatedly confusing — words about red lines serve his policy of sensible caution.