AS SYRIAN TANKS and troops were assaulting the city of Homs on Thursday, brutally restoring the regime’s control over the neighborhood of Bab Amr at the cost of uncounted civilian lives, two senior U.S. officials were testifying to Congress about the Obama administration’s policy. Their message, as Assistant Secretary of State Jeffrey Feltman described it, was that “the demise of the Assad regime is inevitable” and that U.S. policy is “accelerating the arrival of the tipping point” because “the longer the regime assaults the Syrian people, the greater the chances of all-out war in a failed state.”

Yet the administration remains opposed to military intervention to turn the tide against Syrian President Bashar al-Assad or even to protect civilians. It also rejects supplying arms to the opposition. “For more aggressive action,” Mr. Feltman said, “we would need to have a larger international consensus than currently exists.”

The news from Homs, which Mr. Feltman rightly described as “horrific,” ought to prompt a fundamental rethinking of those positions. First, it is far from clear that Mr. Assad’s downfall is inevitable; for now, at least, he is winning his war to stay in power. The steps the United States is taking to “accelerate the tipping point” are too weak to reverse the situation. And the absence of an “international consensus” reflects a failure of American leadership.

Mr. Feltman, a respected professional, correctly spelled out the danger of a prolonged Syrian conflict. The “longer this goes on,” he told the Senate Foreign Relations Committee, “the higher the risks of long-term sectarian conflict, the higher the risk of extremism.” Syria could descend into a chaotic conflict between Mr. Assad’s minority Alawite sect and Sunnis, with Kurds, Christians, Druze and others picking sides, along with neighbors Iran, Iraq, Turkey, Jordan and perhaps even Israel. Al-Qaeda is already attempting to join the fray.

What’s happening now is bad enough: the unchecked slaughter in Homs and elsewhere of women and children with indiscriminate artillery fire directed at residential areas; the massacre of people attempting to flee; and what seems to have been the deliberate targeting of journalists and bloggers attempting to report these crimes. As during the Russian siege of Grozny a decade ago, or the Serbian pounding of Sarajevo in the mid-1990s, a state is inflicting carnage on civilians while the world stands by. Now that Homs has been reduced, Mr. Assad’s forces seem likely to move on to other cities.

The administration’s response remains limited to diplomatic and humanitarian measures, such as urging other governments to tighten sanctions or providing supplies to relief groups. Other countries that have proposed tougher steps, such as giving the opposition arms or creating safe zones for civilians, have met administration resistance. Officials argue that military aid would intensify the fighting — in other words, there would be two sides instead of one. They say the arms might go to extremists. But it is the ad hoc militias attempting to defend civilian neighborhoods that need help in finding weapons, not al-Qaeda.

There are steps the administration could take short of direct intervention. It could work with Iraqi Kurds — who are U.S. allies — to deliver aid to Kurds in Syria. It could provide opposition groups with communications gear and take steps to disrupt the communications of Syrian military units. If it has not already, it should prepare plans to secure the Assad regime’s stocks of chemical and biological weapons — and implement them at the first sign that the regime is preparing to use those arms or allow them to fall into the hands of others.

The Obama administration’s public arguments against the use of force in Syria are simply encouraging a rogue regime to believe it can act with impunity. Until he is faced with a credible threat of force, from the opposition or outside powers, Mr. Assad’s slaughter will go on.