Treimsa can now be added to the list of towns and villages in Syria which up until a few months ago were virtually unknown to the outsider. Treimsa, like Idlib and Houla before it, is now on the international map of massacres and to be forever linked not only to the senseless loss of blood but the inability or the unwillingness to stop the hemorrhage.

Accounts from opposition activists following the attack on Treimsa cite a death toll ranging from over 100 to more than twice that figure - either way one of the bloodiest incidents in 17 months of conflict. The butchery is becoming all too common. So, too, is the blame game as to who is responsible, and the words of outrage, but precious little else, drawn from the outside world.

There is a demand for access for UN observers who were spectators to hours of bombing and gunfire, but were reportedly kept out of Treimsa by Syrian troops. In truth, few think the 120 or so civilian UN officials will prove any more effective in creating the conditions for a ceasefire than the 300 unarmed military observers were in stewarding one.

Whatever the truth about the scale of the carnage and who was responsible, the event in Treimsa will probably not be enough to change the diplomatic stand-off at the UN where Russia is again saying it will veto any Western resolution seeking to impose sanctions and block any steps Moscow views as imposing a regime change in Damascus.

The problem is that the more Russia defends Bashar Al-Assad from any meaningful pressure to change course - including from the Security Council - the more likely it is that the scenario it most fears, one of a Syrian collapse and the emergence of a new state hostile to Moscow, will come about.

Inside Syria is a stalemate as well. The Free Syrian Army (FSA) defines the goal of its struggle as total military victory over the Al-Assad regime rather than any negotiated settlement. Al-Assad says the same, only in reverse. And neither side has complied with the peace plan of Kofi Annan, the special UN envoy, for a political transition based on a ceasefire and negotiations. Under Annan, the rules of engagement were to be framed by UN diplomats, peacekeepers and unarmed observers. Now they are being set by guerrilla fighters and regional armies.

A new Security Council resolution on Syria now under debate might authorize actions ranging from sanctions to military intervention if the violence does not stop. The council is due to vote on July 18. The Treimsa massacre, and those before it, should eliminate any doubt over the need for a coordinated international response. But unless there is a sea change in position, any Security Council resolution against Syria that involves sanctions will draw Russian and Chinese vetoes.

Meanwhile, the casualties on both sides have soared. Nearly 17,000 Syrians have lost their lives since the revolution began in March 2011. But a colossal 5,000 have been killed since April, when Annan first mooted his peace plan and, it appears, regime and rebels have chosen military victory over political compromise as the strategic goal.