It was apparently the mustache that kept John Bolton from being appointed secretary of state. What got him fired as national security adviser?

If reports are to be believed, President Trump removed his third national security adviser in as many years for the same reason that many believed Bolton should not have received the post in the first place: namely, because he was an obstacle to the administration's foreign policy.

No matter how erratic Trump's diplomacy has appeared at times, his basic assumptions have remained the same. It is not in the best interest of the United States to have any more adventures in the Middle East, and we should do everything in our power to extricate ourselves from the situations in which we have found ourselves in Afghanistan, Iraq, and Syria thanks to the blinkeredness of the previous two administrations.

This has meant, among other things, attempting to withdraw as many American troops as we can from Afghanistan as quickly as possible, even if it means making peace with the Taliban. (If only our prior leaders had read Plutarch and the eleventh edition of the Encyclopedia Britannica.) It has meant leaving Bashar al-Assad in Syria to his own devices now that ISIS has been effectively defeated. And, perhaps most important, it has meant leaving the Obama administration's 2015 nuclear accord with the Iranians, not in the hope of pursuing regime change in Tehran but rather to secure a deal that is more likely to secure lasting peace in the region.

But perhaps the single most audacious aspect of Trump's foreign policy has been his approach to North Korea. Every talking head will argue that meeting with Kim Jong Un was not a meaningful achievement and that any president could have done it. If that were so, one wonders why none of them did. Trump's willingness to bypass both NATO and the United Nations in order to pursue the termination of Kim's nuclear program bilaterally is both inspired and necessary given the failure of both to achieve anything of value in the Hermit Kingdom in half a century. (Following through on the process and actually achieving the dream of a nuclear-free Korean Peninsula is another matter, one for which Trump is perhaps less well suited.)

In each of these situations Bolton has been worse than useless. He has undermined the ability of the administration to negotiate with Iran by declaring that our ultimate objective is not arms control — the single overarching theme of American foreign policy since at least 1987 — but regime change, seemingly for its own sake. He has also proven that he is fundamentally unprincipled. For a man who has dedicated his life to undermining the idea of international law and the would-be sovereignty of the United Nations (including while he served as this country's ambassador to that body), it was a bit rich to complain to the president that he should be taking a harder line against Pyongyang because they violated the letter of a U.N. agreement he himself considers essentially meaningless. For Bolton there are no constants in foreign policy except aggression for its own sake.

Does this mean that Trump was foolish for bringing Bolton into his administration in the first place? Not necessarily. There is value in having advisers with a wide range of views, and the implicit threat of Bolton's hawkishness may once have been considered useful to the president in his negotiations. But in practice none of that has panned out. Instead we have had a year and a half of an official contradicting the White House in public and private, to no discernibly worthwhile end. The experiment failed.

"If it was up to John, we'd be in four wars now," Trump is reported to have said of his former national security adviser earlier this year. Thank goodness it was not, and never will be.

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