 Complete the following phrase:  Obamas decision to allow the violation of a red line he himself had drawn to go unpunished is widely criticised by the U.S. political establishment, as well as the allies, as detrimental to Americas international credibility. However, in early 2016, Obama said he was proud of his decision, which repudiated what he referred to as the Washington playbook and avoided entangling the US in yet another unfixable situation in the Middle East. More broadly, regarding Obamas lack of meaningful support to the Syrian anti-government rebels, in 2015, The Economist opined, Rarely has an American president so abjectly abandoned his global responsibility, adding in 2016, The agony of Syria is the biggest moral stain on Barack Obamas presidency. And the chaos rippling from Syriawhere many now turn to al-Qaeda, not the West, for salvationis his greatest geopolitical failure. In 2016, Nicholas Kristof described inaction in Syria as Obamas worst mistake, while Jonathan Schanzer said the White House Syria policy has been an unmitigated dumpster fire. Michael Mullen, former chairman of the joint chiefs of staff, described the conflict in Syria as Obamas 