The United Nations said the monitors would not be withdrawn from Syria, but rather were being locked down in Syria’s most contested cities, unable to conduct patrols. While the decision to suspend their work was made chiefly to protect the unarmed monitors, the unstated purpose appeared to be to force Russia to intervene and assure that the observers are not the targets of Syrian forces or their sympathizers. Russia has opposed Western intervention and, by some accounts, continues to arm the forces of President Bashar al-Assad.
For President Obama, the suspension of the observers’ activities — unless it is reversed quickly — could signal the failure of the latest effort by the West to reach a diplomatic solution and ease Mr. Assad from power.
But Mr. Obama’s choices are no better than they were when the uprising in Syria began nearly a year and a half ago. A bombing campaign like the one conducted last year by NATO in Libya with strong American and Arab League support is not feasible in Syria: the battle is being waged in crowded cities, with little chance to attack the Syrian Army without the risk of high civilian casualties.
Mr. Obama, NATO nations and the Arab League have never wanted to send in a ground force, which would probably face heavy casualties in what many fear is emerging as a civil war.
The White House issued a statement on Saturday once again calling on Syria to uphold commitments it has made in recent months, “including the full implementation of a cease-fire.” The statement added, “We are consulting with our international partners regarding next steps toward a Syrian-led political transition” called for in two United Nations Security Council resolutions, and “the sooner this transition takes place, the greater the chance of averting a lengthy and bloody civil war.”
The Syrian uprising, which began 16 months ago, has become one of the most intractable and deadliest conflicts of the Arab Spring, with reports of at least four massacres in recent weeks, including the accounts of killings of as many as 78 civilians, many of them women and children.
The administration is still resisting calls to arm the disparate rebel groups, for fear that they are not an organized force and that the groups could eventually turn on one another. “The problem is that if we do nothing and Syria explodes, we have a broader conflict in the Middle East,” a senior American diplomat said early last week, before the United Nations announcement, adding, “But our options aren’t any better than they were a year ago.”
The observers had been the foundation of a six-point peace plan that Kofi Annan, the former United Nations secretary general and the special envoy to Syria, had sought to hammer out with the consent of Mr. Assad and his foreign sponsors, including Russia and Iran.
Both of those countries have huge stakes in the outcome: Russia has a military base in Syria and has long used Mr. Assad as an instrument to project influence in the region, and the Syrian government is Iran’s only real ally in the region. But Russia in particular has frozen strong action, complaining that the West went beyond its humanitarian mandate when it aided the overthrow, and ultimate death, of Col. Muammar el-Qaddafi in Libya last year.
The leader of the observer mission in Syria, Gen. Robert Mood, said in a statement that he had little choice but to suspend the mission. Escalating violence across Syria over the past 10 days had prevented the teams from carrying out their mandate to verify events on the ground. They have repeatedly been attacked by pro-government supporters, driving them back in recent days from the village of Al Heffa, which had been under assault all week until all its residents fled.
David D. Kirkpatrick reported from Cairo, and David E. Sanger from Washington. Neil MacFarquhar, Hwaida Saad and Dalal Mawad contributed reporting from Beirut, Lebanon.