Sam Roggeveen asks: 'What is controversial about a US president saying that there are a whole bunch of conflicts the US will not get involved in?'

True, superpowers don't clean windows. But controversy, in my view, is unavoidable when a president narrows US interests to the point that a wholesale regional crisis in the Middle East spurs only a token US response. That's rather more than a spat between China and Vietnam, or even Russia's bad behaviour in the former Warsaw Pact countries.

The opportunity for early American air strikes against ISIS has been lost. Any future military action will find it much harder to successfully strike the group's leadership. When the capital is under attack no amount of pious lecturing about the principles of good government will replace practical military support. The price of American inaction is the likelihood that an even bigger and more complicated American response will be required later. That is because America's interests in the Middle East balance of power are so substantial that not even Barack Obama can ignore them forever.

As with many commentators, Sam's distaste of George W Bush and the 2003 Iraq War clouds his judgement about what should be America's role in 2014.

The situation Iraq faces today isn't only a consequence of the invasion of 2003. What we're seeing now wouldn't be happening without the Obama Administration's willingness to tolerate a vacuum in Syria and its half-hearted acquiescence to Maliki's rejection of US forces being based in Iraq. Opponents of the 2003 war continue their cottage industry of finding fresh ways to be unhappy about it. As creative as that might be, it's as unhelpful in solving Iraq's current dilemmas as, well, a visit from John Kerry.

American overreach won't be solved by ignoring strategic problems. While it is true that some conflicts can and should be avoided by the US, Obama cannot avoid engagement in an imploding Middle East. Obama might find his current choices unappetising, but pretending that America can sit out this fight is just not realistic.