Major powers agreed on 12 February to temporarily halt combat in Syria, but Russia pressed on with bombing in support of its ally President Bashar al-Assad, who vowed to fight until he regained full control of the country. In an interview with Dubai-based Orient TV in Munich, US Secretary of State John Kerry said that if the peace plan fails, more foreign troops could enter the conflict.

If the Assad regime does not live up to its responsibilities and if the Iranians and the Russians do not hold Assad to the promises that they have made… then the international community obviously is not going to sit there like fools and watch this. There will be an increase of activity to put greater pressure on them, Kerry told Orient TV. There is a possibility there will be additional ground troops, he added.

Although billed as a potential breakthrough, the cessation of hostilities agreement does not take effect for a week, at a time when Assads government is poised to win its biggest victory of the war with the backing of Russian air power. If implemented, the deal – hammered out during five hours of late night talks in Munich – would allow humanitarian aid to reach besieged towns.

It was described by the countries that took part as a rare diplomatic success in a conflict that has fractured the Middle East, killed at least 250,000 people, made 11 million homeless and sent hundreds of thousands fleeing into Europe.