JOHN F. KERRY acknowledged to a group of congressmen over the weekend that the Obama administration’s policy in Syria is failing, according to two Republican senators. If so — Mr. Kerry’s spokeswoman disputed the account — he would deserve credit for finally recognizing realities that he and President Obama have glossed over for too long.

For months Mr. Kerry has been assuring the world that Syria’s epic carnage could be best addressed by peace negotiations in Geneva. Their purpose, he insisted, was “specifically and solely” to create a transitional government to replace the regime of Bashar al-Assad. Meanwhile, he and Mr. Obama repeatedly cited the Assad regime’s agreement to hand over its stocks of chemical weapons as mitigating the threat Syria’s civil war poses to U.S. interests.

These assertions were never credible. Now both have become indefensible. According to United Nations envoy Lakhdar Brahimi, the Geneva talks, which broke off last week, “haven’t achieved anything.” Not only has the regime refused to engage in the discussion of a new government that Mr. Kerry promised but it also has declined to agree to the humanitarian steps that Mr. Brahimi was hoping for — including opening supply routes to hundreds of thousands of civilians who are being deliberately starved of food and medicine. As for the chemical weapons, the State Department reported last week that Mr. Assad is deliberately stalling the process after handing over a mere 4 percent of the stockpile.

Far more serious threats to the United States from Syria go unaddressed. One was spelled out last week by Director of National Intelligence James R. Clapper Jr., who told Congress that Syria “is becoming a center of radical extremism and a potential threat to the homeland.” Once again, terrorists linked to al-Qaeda may be using territory they control to plot attacks against the United States, even as Mr. Kerry pursues his long-shot diplomacy and Mr. Obama offers excuses for inaction.

The president claims that the United States could not positively influence the situation in Syria unless it launched an Iraq-style invasion. Mr. Assad demonstrated that this is untrue in his response to Mr. Obama’s threat of targeted airstrikes last summer — a quick agreement to hand over chemical arms. A similar show of U.S. willingness to use limited force could, at the least, compel Mr. Assad to fulfill that deal. But it could also be wielded to put an end to the unconscionable crimes against humanity the regime is committing in full view of the world — from blockades that have caused the starvation of children to the mass execution of prisoners and use of “barrel bombs,” Scud missiles and other indiscriminate weapons on apartment buildings, hospitals and schools.

As a starting point, the administration could join an effort by allies on the U.N. Security Council to win passage of a resolution that calls on Syria to cooperate with the delivery of humanitarian supplies and authorizes U.N. agencies to operate in areas outside government control. Russia may resist the resolution, but with the Sochi Olympic Games about to begin, even Vladi­mir Putin may hesitate to be seen vetoing food deliveries to famished children.

With or without U.N. action, it is time for the Obama administration to reconsider how it can check the regime’s crimes and the growing threat of al-Qaeda. As Mr. Kerry reportedly conceded, for now it has no answers.