SO FAR, a U.N. monitoring mission in Syria has had one tangible effect: It has gotten people killed. On Sunday and Monday, monitors toured neighborhoods in the city of Homs and in the Damascus suburbs of Doura and Zabadani. When they left, the areas they visited were shelled, and security forces carried out sweeps in which civilians suspected of speaking to the monitors were taken from their homes and shot or had their houses burned down.

“We have credible reports that . . . these people who approach the observers may be approached by security forces or Syrian army and harassed or arrested or even worse, perhaps killed,” Ahmad Fawzi, a spokesman for U.N. envoy Kofi Annan, confirmed to U.N. television.

How did Mr. Annan and the U.N. Security Council react to these horrific reports? By urging the deployment of more monitors. “There is a chance to expand and consolidate the cessation of violence,” Mr. Annan told a closed session of the Security Council, according to reporting by The Post’s Colum Lynch. “Observers not only see what is going on, but their presence has the potential to change the political dynamics.”

Those words well captured the delusion of Mr. Annan and those who support his diplomacy. There has been no “cessation of violence”; numerous Syrians have been killed every day since the supposed U.N. cease-fire went into effect April 1. Thirty people were reported killed on Tuesday alone. The observers are not “changing dynamics” but providing cover and even targets for the regime of Bashar al-Assad.

Yet even when faced with stark facts like the reprisal killings in Homs, the ambassadors sound unfazed: “Targeting by Syrian regime of those speaking w/UN monitors outrageous but not unexpected,” tweeted the Obama administration’s U.N. ambassador, Susan Rice. This raises two questions: If such atrocities were predictable, why did the United States vote to send the U.N. monitors to Syria? And why does it support their continued deployment?

The evident answer is that the Obama administration, like its “partners” on the Security Council, wishes to be seen as doing something to stop the bloodshed in Syria without having to commit resources or exert leadership. Sadly, this is far from the first such failure. In a blog at Foreign Policy’s Web site, Michael Dobbs has been documenting the eerie resemblances between the United Nations’ handling of Syria and its history in Bosnia — where an attempt to stop attacks on civilians by dispatching lightly armed peacekeepers in the 1990s led to the worst massacre in postwar European history.

As Mr. Dobbs reported, a 1999 report signed by Mr. Annan himself concluded that the Bosnia mission was “at best, a half measure” and a poor substitute for “more decisive and forceful action to prevent the unfolding horror.” Said that Annan report: “We tried to keep the peace and apply the rules of peacekeeping when there was no peace to keep.”

It’s bad enough that the Obama administration refuses to learn the lessons of previous failures. More galling is its claim that it has made the prevention of atrocities a priority — as Mr. Obama did Monday in announcing the creation of an “atrocities prevention board.” “We see the Syrian people subjected to unspeakable violence, simply for demanding their universal rights,” he said. “And we have to do everything we can.”

Is sending unarmed monitors to besieged cities and shrugging when the people they visit are murdered everything the United States can do? Even in an election year, the answer has to be no.