The massacre in the Syrian town of Houla near Homs on Friday has put the UN-backed peace-plan for the country in jeopardy, as the country's rebel forces have announced that they would no longer abide by the ceasefire and local protestors have started to call on UN observers to leave the nation.

The regime itself has denied responsibility for the killings, blaming Al-Qaeda, as they have done after all large bombings and shootings. The Guardian's Martin Chulov spoke to Houla resident Abu Jaffour, who said:

Al-Qaida hiding in the mountains? They expect people to believe that? These mountain areas are the Allawite villages and Houla is full of the families of the Free Syrian Army [FSA].

Wissam Tarif, Avaaz.org's Arab world campaigner, argued that:

This is not just some angry guys who went and killed these families. This is a state policy, a regime policy, spreading sectarian tensions. People in Houla are going to retaliate. They will enter into yet another cycle of violence.

At least a hundred people died in the shelling of Houla, including 49 children, 22 of whom were nursery-age. The UN security council unanimously condemned, "in the strongest terms", the killings, where it said that civilians had been shot "at close range" and suffered "severe physical abuse". The attacks also involved "a series of government artillery and tank shellings on a residential neighbourhood".

The security council had called the emergency meeting on Sunday following the rejection by Russia of a draft statement produced jointly by France and Britain. Today, William Hague, Foreign Secretary, is in Moscow on a long-planned but newly important meeting with his Russian counterpart. On Sunday, Hague said:

Our urgent priority is to establish a full account of this appalling crime and to move swiftly to ensure that those responsible are identified and held to account.

 And he tweeted that he would:

[Call] on Russia to support rapid & unequivocal pressure on Assad regime and accountability for crimes.

President Obama is joining efforts to gain Russian co-operation over Syria, and the New York Times reports that he is proposing to Vladimir Putin a plan similar to the managed transition underway in Yemen at the moment.

Helene Cooper and Mark Landler write for the paper that:

After months of violent unrest, [Yemini] President Ali Abdullah Saleh agreed to step down and hand control to his vice president, Abdu Rabbu Mansour Hadi, in a deal arranged by Yemen’s Arab neighbors. Mr. Hadi, though later elected in an uncontested vote, is viewed as a transitional leader. . .

The Yemen example has been widely discussed in Moscow, so much so that the option has become known by its Russian term, "the Yemenskii Variant," even in the United States. In part, that reflects Russia’s desperation for a solution to the crisis in Syria, where, the United Nations says, thousands of civilians have been killed since protests began there in March of last year.

The global conversation appears to have moved from debating whether something ought to be done, to debating what it should be. To that extent, the horror in Houla may represent a turning-point in the Syrian struggle.