US President Barack Obama arrived in Russia Thursday for the G20 summit, where he is trying to seek more international support over his push for military action against the Syrian regime, hours after US Congress backed an amended resolution authorizing the strike.

Ben Rhodes, Obama's Deputy National Security Advisor for Strategic Communication, said the president would explain the current thinking of the US to its allies and partners.

The Chinese foreign ministry on Thursday called on relevant sides to "remain calm" and adhere to political measures on the Syria issue.

Spokesman Hong Lei said that unilateral military action is contrary to international law and basic norms of international relations, adding that the focus of the summit should be on addressing the global economic slowdown and promoting international economic and financial governance, not on Syria.

The US Senate Committee on Foreign Relations earlier approved an amended resolution with the vote of 10 to 7 that would authorize US military intervention with a 90-day deadline and bar American boots on the ground for combat purposes.

In the face of possible strikes, Syrian Deputy Foreign Minister Faisal Muqdad was quoted by the AFP as saying that his government is ready to retaliate in the event of foreign military action and the regime will "not change position even if there is World War III."

Tian Wenlin, a research fellow on Middle Eastern studies at the China Institute of Contemporary International Relations, told the Global Times that Bashar al-Assad's government hopes to pacify domestic fears over the US potential military strikes by speaking in a tough voice.

With the number of Syrian refugees passing 2 million, UN humanitarian chief Valerie Amos arrived in Damascus Thursday for talks with officials.

Rima Kamal, spokeswoman for the International Committee of the Red Cross (ICRC) in Syria, told the Global Times that the ICRC is very concerned about the potential escalation of violence in the face of the strike mulled by the US. "Although the strike has not even started, and it is just being debated right now, there are actually thousands of people who have crossed to Lebanon over the past couple of days," she said.

The ICRC said it is trying to prepare in all cases to remain operational, including increasing stocks of food and medications, although it is very difficult to predict what will happen if a US strike takes place. "We couldn't know at this point whether there will be the space for humanitarian work to take place as a result of escalation of violence," Kamal said, raising the biggest concern that the ICRC may not get full access to the affected areas as it has experienced during the past two years.

Agencies contributed to this story