Since President Trump called for an escalation of the war in Afghanistan, he has been savaged by some of his most ardent former supporters. From Breitbart to the columnist Patrick Buchanan, advocates of an "America First" foreign policy have been appalled to see their man so completely embrace the can-kicking policies that have given America its longest war.

But they shouldn't be surprised. The most popular positioning for a candidate is to say that he won't get involved in a conflict unless he has a plan to win, and, if we are already involved in a conflict, he will give the military the tools (and the operational latitude) to finish the job. So it's not an accident that this is how Trump positioned himself in the primaries and in the general election — as, in different ways, Presidents Bush and Obama had done before him.

Trump excelled Bush and Obama not in calling for a new course in foreign policy, but in belligerently seizing both sides of most foreign policy questions. With respect to the Middle East, Trump claimed to have been against the invasion of Iraq and the intervention in Libya before they happened (though there was little evidence of this opposition). But he also claimed to have opposed the withdrawal from Iraq, and he called for a significant escalation of the war against ISIS, whether that meant a stepped-up bombing campaign or an invasion to "take their oil." Moreover, he opposed an Iran deal aimed at resolving the nuclear question as thoroughly as possible without resorting to military action.

Though some of his supporters clearly believed otherwise, this was not the posture of an advocate of realism or restraint, someone who saw America's foreign policy taking on challenges it was ill-equipped to meet. Rather, it was the posture of a Monday morning quarterback convinced that the only reason America wasn't "winning" is that the people making policy were idiots.

President Obama, when he gave the military the escalation it wanted in Afghanistan, was willing to own a policy that he had advocated as a candidate even though he had serious doubts about its efficacy. Perhaps he thought he had the political capital to say he had tried, and to reverse course if the escalation failed to stabilize the country. Once Osama bin Laden was killed, he had the perfect opportunity to declare victory and go home. By failing to do so, he ushered in the subsequent era of inertia that Trump inherited.

So it should be no surprise, that, once in office, Trump repeatedly demanded an alternative to either staying the course in Afghanistan or pulling out — some strategy that promised victory — and that, when it became apparent that no such strategy was available, he opted for staying the course, indefinitely and without clear objective. What little capital Trump had amassed was not earned by promising to bring America's troops home, but by promising to win.

Genuine advocates of a more restrained and realistic foreign policy are now in a difficult position. The president has every incentive to find a scapegoat for the all-too-probable failure of his new Afghanistan policy, and no scapegoat would do better than domestic opposition — particularly if it comes from the left. But war opponents on the left and right appear less likely than ever to cooperate in today's almost completely polarized climate. And in the absence of concerted opposition from outside, both elected officials and increasingly influential military leaders have every reason to prioritize keeping failure from happening on their watch, whatever the long term cost to the country.

It is all the more vital, then, for prominent opponents on the right to reach across the ideological divide and demand the rationalization of our foreign policy that is perpetually promised and never delivered. Stephen Bannon ended his tenure in the White House with a call to left-wing journalist Robert Kuttner to ham-handedly make common cause on trade policy. If he was serious about his lonely opposition to the administration's Afghanistan policy, it is time for him to place similar calls to everyone from Fred Kaplan to Tom Ricks to Michael Kazin, to try to build similar bridges on foreign policy.

He'd likely fail, as he's likely to fail to build a cross-partisan movement for a more nationalistic trade policy. But at least he'd make it that much harder for the administration to tar any left-wing opposition that does develop with the charge of aiding America's enemies and stabbing our military in the back.