There is no obligation to try every other option if the other options are unlikely to work. People are unjustly suffering now, and we have an obligation to end that suffering as quickly and as efficiently as possible. Sanctions and asset-freezing are notoriously ineffective on oil-producing countries like Syria. Going through the motions of attempting to pass authorization for these actions through the United Nations Security Council, attempting to get the entire world to comply with the sanctions and then watching these actions not help anything. All this will do is prolong the suffering of the Syrian people.