Obama's decision to allow the violation of a red line he himself had drawn to go unpunished was widely criticized by the U.S. political establishment and some U.S. allies as being detrimental to America's 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 Obama's 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 Obama's presidency. And the chaos rippling from Syria—where many now turn to al-Qaeda, not the West, for salvation—is his greatest geopolitical failure." In 2016, Nicholas Kristof described inaction in Syria as "Obama's 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 "Obama's Rwanda". This is in lieu of the CIA-backed operation Timber Sycamore, which provide weapons and trainings to anti-government rebels, but proved to be ineffective by the end of the Obama presidency.