MUNICH — Hopes of securing a temporary truce in Syria within a week dimmed Saturday as Syrian forces tightened the noose around rebel-held parts of Aleppo and Russia’s foreign minister put the chances of a quick truce at less than 50 percent. His comments and strong words from U.S. Secretary of State John Kerry underscored deep U.S.-Russian disagreements over Syria.

Further complicating the picture, Turkey’s foreign minister said his country and Saudi Arabia may launch ground operations against the Islamic State group in Syria.

Diplomats from countries with interests in Syria’s five-year civil war – including the U.S., Russia, Turkey, Iran and Saudi Arabia – agreed Friday to work toward a temporary “cessation of hostilities” within a week. They also agreed to “accelerate and expand” deliveries of humanitarian aid to besieged Syrian communities this week.

Still, officials acknowledged that the test would be turning commitments on paper into reality on the ground – and it wasn’t clear whether deep differences regarding the truce and which groups would be eligible for it could be overcome.

The truce deal in Munich came as Syrian forces, aided by a Russian bombing campaign, are trying to encircle rebels in Aleppo, Syria’s largest city, and cut off their supply route to Turkey.

Speaking Saturday at the Munich Security Conference, Russian Foreign Minister Sergey Lavrov – pressed to say how confident he is that a “cessation of hostilities” will be implemented within a week – replied: “49” out of 100 percent.

Lavrov said comments by U.S. officials raised the impression that their aim was to stop Russia’s military operation in Syria while the U.S.-led coalition’s continues – “although we are fighting the very same … organizations which the U.N. Security Council has designated as terrorist organizations.”

Kerry, who negotiated the deal with Lavrov and others, said “we will, we will make it work.”

Still, Kerry’s repeated allegations that Russian airstrikes in Syria have not been directed at terrorists but rather at moderate opposition groups supported by the U.S..

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.