The enemy of my enemy might be my friend, but what if the enemy of my enemy isn't that good at being the enemy of my enemy? And simultaneously, that the enemy of my enemy is also the enemy of my friend?

That, in summation, is why Turkey cannot be given significant U.S. military support in Syria. It's relevant because Turkey is requesting major U.S. military support in return for finishing off the Islamic State in Syria. Top U.S. officials including national security adviser John Bolton are now negotiating this support with President Recep Tayyip Erdogan's government.

It's a very bad idea.

First off, under the always unreliable Erdogan, the Turks are unreliable partners in defeating ISIS. While Turkey shares that interest at a basic level, its fundamental focus in Syria is in crushing the Kurds. While this Turkish crackdown on the Kurds was always inevitable, its ferocity and territorial reach will be greatly enabled by America's withdrawal from Syria. That said, were the U.S. now to provide intelligence and targeting platforms to the Turkish military (which is what Turkey would need to fight ISIS), they will almost certainly manipulate those platforms to target the U.S.-allied Kurdish YPG militia as well as ISIS. That will leave the U.S. in the impossible moral and political scenario of helping Turkey to kill our erstwhile allies. It would be a disgrace.

But that's only half the problem here. The second challenge is that Turkey cannot accomplish the anti-ISIS mission. The simple challenge is that the Turkish armed forces are not built for the speed, mobility, and hyper-intelligence driven task that defeating ISIS holdouts will entail. The Turkish military is a force of mass designed to defeat an enemy force of mass. Forces of mass do badly against mobile skirmishing units (which now define ISIS in Syria). Turkey's military mass design is why the smaller and far less well-equipped PKK terrorist group has been able to maintain a structured military presence under so many years of Turkish pressure. In short, the Turkish military is ill-designed to chase down and destroy terrorist groups. But where it does do so, the Turkish military tends to follow the Russian example of counter-terrorism. Which is to say, in killing a lot of civilians. The U.S. military can mitigate these weaknesses but not without handing over boutique intelligence platforms to Turkey (which may end up in Russian or Chinese hands), or without putting specialized U.S. military units under an excessive degree of Turkish control. If President Trump continues on this route, he'll be turning "America First" into "Turkey First via American power."

All of this raises a question: What on Earth is the White House thinking?

In part, this seems to reflect John Bolton's desperation to salvage the broader strategic interests that motivated the U.S. military deployment in Syria — namely, constraint of Iranian supply movements from Iran to southern Lebanon, and pressure on Bashar Assad. Reports suggest that Bolton recently wrote a memo noting "that the administration’s prior policy objectives in Syria were not being changed. Those goals have included defeating Islamic State, evicting Iranian-commanded forces and pursuing a diplomatic end to the civil war."

Again, however, if true, Bolton's contention is absurd. In America's withdrawal from Syria, Russia is the archon of what happens next. Altering Iranian activity in Syria, or influencing the Syrian post-war political track, or nudging Turkey to take major actions is now dependent on Vladimir Putin's whims. There is no way that the Russian leader is going to unleash Erdogan to serve U.S. interests. Indeed, for the sole rationale of embarrassing the U.S., the Russians are likely to allow ISIS a limited territorial rebirth. Remember, Russia does not see the Syrian situation through the prism we do. Putin sees Syria as a means to usurp U.S. relationships in the broader Middle East and as a way to hurt the U.S. in a broader geopolitical struggle.

If President Trump wants to defeat ISIS and Bolton wants to support U.S. interests, they need to either keep U.S. military forces in Syria or ramp up the CIA's paramilitary presence. Otherwise they simply need to accept they've lost.