AFTER MONTHS of hesi­ta­tion, the Obama administration has finally recognized what the people of Syria have been making clear for the past four months: that President Bashar al-Assad “has lost legitimacy” and “failed to deliver on the promises he has made,” as Secretary of State Hillary Rodham Clinton put it on Monday. “President Assad is not indispensable and we have absolutely nothing invested in him remaining in power,” Ms. Clinton said. That qualifies as news: For months the administration behaved as if it wished to preserve Mr. Assad as a guarantor of stability in his country or a potential peace partner with Israel. Up until this week it has described political reforms led by him as a potential solution to the country’s crisis.

Sadly, the event that appeared to trigger the change in rhetoric was not the continuing slaughter by Mr. Assad’s forces of the courageous Syrians who have turned out in dozens of cities and villages to demand an end to his dictatorship. Instead, the tougher language followed an assault on the U.S. Embassy and ambassador’s residence in Damascus that was carried out by thugs who were bused in by the regime and that was orchestrated by one of its television stations. The mob smashed windows, hurled rocks and tomatoes and painted slogans before moving on to the French Embassy, which they also attacked.

Some Syrians may wonder why an ugly but non-lethal incursion on Western diplomatic property got a reaction that the slaughter of some 1,500 people with tanks and helicopter gunships failed to elicit. But we hope they will also remember the superb diplomacy of U.S. Ambassador to Syria Robert S. Ford, who, like his French counterpart, traveled last week to the city of Hama, which has been taken over by the opposition. Mr. Assad’s tanks ring the city, and many residents fear a murderous assault. The American ambassador’s presence may have forestalled such an attack; it also allowed Mr. Ford to observe and report that, contrary to the regime’s propaganda, the Hama protesters were unarmed and have not attacked government buildings or officials.

Mr. Ford’s mission was a demonstration that — despite what is frequently heard from administration officials in Washington — it is possible for the United States to help Syrians free themselves from the Assad dictatorship. Declaring Mr. Assad “illegitimate” is an important signal; it would have still more impact if President Obama, who has spoken publicly on Syria only twice in four months, were to give Mr. Assad the same rhetorical shove he delivered to Egypt’s Hosni Mubarak and Libya’s Moammar Gaddafi.

The administration should also be working to step up economic pressure on the regime, which is highly vulnerable to a collapse of foreign revenue. Nearly a month ago, State Department officials held a briefing to describe how they were preparing new sanctions, including efforts to block Syria’s exports of oil and gas. Nothing has happened since then. Turkey, to which the administration has ceded leadership on the Syrian crisis, continues to equivocate about whether Mr. Assad’s regime is redeemable; Ms. Clinton should press for a stronger stance when she travels to Istanbul later this week.

The administration appears to have recognized, belatedly, that Mr. Assad will never recover from the stain of the bloodshed he has caused. As Assistant Secretary of State Michael Posner testified to Congress on Tuesday, the “government continues to be the real source of instability within Syria.” It’s good that the Obama administration has finally spoken that truth. Now it must act on its words.