Russian President Vladimir Putin restated his opposition to any strike, saying it would destabilise the region.
US President Barack Obama said action was necessary in reaction to the use of chemical weapons in Syria.
A joint statement from the US and 10 other nations called for a strong international response.
The US government accuses President Bashar al-Assad's forces of killing 1,429 people in a poison-gas attack in the Damascus suburbs on 21 August. Mr Assad has blamed rebels for the attack.
US President Barack Obama said action was necessary in reaction to the use of chemical weapons in Syria.
A joint statement from the US and 10 other nations called for a strong international response.
The US government accuses President Bashar al-Assad's forces of killing 1,429 people in a poison-gas attack in the Damascus suburbs on 21 August. Mr Assad has blamed rebels for the attack.
