THE CAUSE OF FREEDOM in Syria took a blow Tuesday when Russia and China vetoed a watered-down U.N. Security Council resolution on the slaughter of peaceful protesters by the regime of Bashar al-Assad. But there was a silver lining: The governments of Vladi­mir Putin and Hu Jintao finally were held accountable before the people of Syria and the larger Middle East for their cynical and self-interested obstructionism.

For months the two governments have prevented Security Council action on Syria, even though the United Nations’ human rights commission has reported at least 2,700 people killed and warned that the regime’s actions may constitute crimes against humanity. With its 1989 Tiananmen Square crackdown still in mind, Beijing routinely opposes what it regards as “interference in the internal affairs” of other dictatorships. But China might have allowed the European-drafted resolution on Syria to pass had it not been for the resolute stance of Russia, which has sold billions in weapons to Mr. Assad.

The Kremlin might have been expected to show the same sagacity as Turkish President Recep Tayyip Erdogan, who formerly cultivated the Assad regime but now, recognizing that it is probably doomed, has turned against it. To his credit Mr. Erdogan on Wednesday brushed off the U.N. vote and reiterated that Turkey will soon adopt sanctions. But Mr. Putin, unlike the politically skilled Turkish president, has little interest in how Russia is perceived by the people of Syria or the Middle East. He is also likely bound by the corruption networks in his government that increasingly drive official policy — and feast on arms sales.

The cheering news is that European governments finally decided to force a Security Council vote — and that the Obama administration’s U.N. ambassador, Susan E. Rice, called Mr. Putin to account. “The United States is outraged that this council has utterly failed to address an urgent moral challenge,” began her passionate and searing intervention. “Today, the courageous people of Syria can now clearly see who on this council supports their yearning for liberty and universal rights — and who does not.”

Moscow and Beijing sought to justify their vetoes by citing NATO’s bombing in Libya and claiming that a Security Council resolution on Syria would become a prextext for another intervention. Ms. Rice rightly dismissed that excuse: “Let there be no doubt: This is not about military intervention. This is not about Libya. That is a cheap ruse by those who would rather sell arms to the Syrian regime than stand with the Syrian people.”

Too often in the past nine months, people seeking to end autocracy in the Middle East have had cause to wonder whether the United States stands with them. Syria early on was no exception: The administration’s first reaction to the uprising against Mr. Assad was to label him “a reformer.” But the brave diplomacy of Ambassador Robert S. Ford in Damascus and Ms. Rice’s crystalline statement Tuesday have helped ally the United States with the people of Syria. They will remember — just as they will remember their cynical betrayal by the dictators of China and Russia.