IS threatens Assad's Aleppo push

"Islamic State" (IS) terrorists cut off the main supply route to the Syrian city of Aleppo on Tuesday as the regime of President Bashar al-Assad redoubled efforts to completely take the city back from the jihadists.

Troops loyal to Damascus were forced to cede the road as well as the town of Khanaser, which lies along it.

"The clashes are ongoing, the regime recovered four of seven [lost positions]. [The road] is still cut," said the head of the Syrian Observatory for Human Rights to news agency Reuters.

Without the supply road, the northern city of Aleppo, the country's main commercial center, is effectively cut off from the center and west of the country.

The clashes came amid increasing international pressure to prioritize reduction in violence over immediate political change.

"It may be too late to keep it as a whole Syria if we wait much longer," US Secretary of State John Kerry told the Senate Foreign Relations Committee on Tuesday. He added that, even if the Russia-backed government forces are able to recapture Aleppo, it remained difficult to hold onto territory in many parts of the conflict-ridden country.

Kerry: Obama has Plan B

The US top diplomat also put aside doubts about a new ceasefire deal, saying Obama has other options if the current diplomatic plan does not pan out.

"We're going to know in a month or two whether or not this transition process is really serious ... Assad himself is going to have to make some real decisions about the formation of a transitional governance process that's real. If there isn't ... there are certainly Plan B options being considered," Kerry said.

Earlier on Tuesday, Damascus announced that it had signed off on the truce agreement, along with an umbrella group of rebel factions. Put in motion by the US and Russia, the ceasefire deal does not include attacks on IS targets, which would still be ongoing.

Some rebels have criticized this facet of the ceasefire, saying it will allow the government to continue bombing areas where IS militants may be mixed in among more moderate groups.

es/rc (AP, Reuters)