President Barack Obama has said the US cannot “turn a blind eye” to the use of chemical weapons in Syria.He was speaking after returning to the US from a G20 summit in Russia, which failed to produce international agreement on military action in Syria. The US accuses President Bashar al-Assad’s forces of killing 1,429 people in a poison gas attack on 21 August. EU foreign ministers say there should be no action before the UN reports back on chemical weapons attacks in Syria. Mr Obama faces a tough week of trying to persuade Congress to authorise military action. He will also seek public support in a White House address on Tuesday. Mr Assad and his ally President Vladimir Putin of Russia blame rebels for the attack. In a radio and internet address, Mr Obama said he understood that the American people were “weary after a decade of war” and insisted this would not be an “open-ended intervention” akin to the wars in Iraq and Afghanistan. “But we are the United States of America. We cannot turn a blind eye to images like the ones we’ve seen out of Syria. “Failing to respond to this outrageous attack would increase the risk that chemical weapons could be used again, that they would fall into the hands of terrorists who might use them against us, and it would send a horrible signal to other nations that there would be no consequences for their use of these weapons. “All of which would pose a serious threat to our national security.” Any action, President Obama said, would be “limited both in time and scope – designed to deter the Syrian government from gassing its own people again and degrade its ability to do so”.