A civil defence member reacts at a site hit by what activists said were three consecutive air strikes carried out by the Russian air force, the last which hit an ambulance, in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria January 12, 2016.

A Western official said on Wednesday that Russia has made a proposal to begin a ceasefire in Syria on March 1, but the official said no agreement has been reached on the Russian offer.

The official said the United States has concerns about some elements of the Russian proposal.

Meanwhile, several United Nations Security Council members also pressed Russia on Wednesday to stop bombing around Syria’s Aleppo in support of a Syrian military offensive and allow humanitarian access ahead of a crucial meeting of major powers in Germany on the conflict.

The 15-member Security Council met behind closed doors to discuss the situation after the U.N. warned that hundreds of thousands of civilians could be cut off from food if Syrian government forces encircle rebel-held parts of Aleppo.

“Russia’s air strikes have been a direct cause of this crisis around Aleppo,” New Zealand’s U.N. Ambassador Gerard van Bohemen told reporters after a briefing by U.N. aid chief Stephen O’Brien. New Zealand and Spain requested the meeting.

Envoy: Russia strikes boost ISIS

Earlier, the U.S. envoy to the coalition against ISIS said on Wednesday that Russian airstrikes in Syria are boosting the militant group because of the toll they are taking on U.S.-backed opposition fighters.

“What Russia’s doing is directly enabling ISIL,” the envoy, Brett McGurk, told a hearing of the House of Representatives Foreign Affairs Committee, using an acronym for Islamic State.

He left the hearing for a flight to Germany, where world powers are meeting on Thursday to try to revive the first effort in two years to negotiate an end to the war in Syria after it faltered last week.

Rebel groups have been urging U.S. President Barack Obama to do more to stop Russian bombing raids that have left them on the verge of collapse ahead of the talks.

McGurk said Washington is committed to securing a ceasefire, but needs to consider options in case the diplomatic push falls short.

Under questioning from House members frustrated over the sputtering anti-ISIS campaign, McGurk said the United States and its allies were making progress against the group, but face major challenges. “Our progress will not always be linear, and we should expect setbacks and surprises,” McGurk said.

Committee members said they wanted Washington to do more.

“These gains have been too slow to come and too limited,” U.S. Representative Ed Royce, the panel’s Republican chairman, said.

McGurk also acknowledged Islamic State’s growing influence outside of Iraq and Syria.

He said its branch in Libya is the greatest cause for concern, given its attacks in the chaotic North African country and the threat it poses to U.S. partners such as Tunisia and Egypt.

He did not rule out U.S. aid airdrops to help ease the humanitarian crisis in Syria. “We’re looking at all options on the humanitarian side,” McGurk said.

Related articles across the web

• U.N. Security Council condemns North Korea rocket launch
• Rand Paul's awkward presidential campaign in 1 perfect cartoon
• UN Security Council to hold emergency meeting on North Korea
• UN Security Council to hold emergency talks on N. Korea
• UN SC unanimously condemns North Korea's rocket launch
• UN Security Council condemns N Korea rocket launch
• Thousands Flee as Syrian Forces, Backed by Russia and Iran, Encircle Aleppo
• UPDATE2: U.N. Security Council condemns N. Korea launch using missile technology
• UN Security Council condemns North Korean rocket launch
• UN Security Council to Meet over North Korea Rocket Launch