Over the holiday break I finally finished Bob Woodward’s “Fear.” The book itself had a surprising effect on me; it made me think more highly of Donald Trump. That is admittedly an easy task, because I do not think that much of the 45th president. That said, “Fear” highlights a dilemma that all post-Cold War presidents have faced: the ratchet effect of military intervention.

The most powerful critique of liberal internationalism is that once the United States sends its military into a country, it seldom leaves. Even the successful cases of post-Cold War intervention have an open-ended U.S. military presence, with advocates pushing for even more. The less-successful cases require even more investments in blood and treasure. Contrary to popular belief, the U.S. military does not like to launch new wars. That said, it also likes to finish what it started, which means there is very little military appetite for withdrawing troops from Syria or Afghanistan.

Few military interventions are solved within the span of a single presidential administration. So, any presidential choice to intervene creates a policy problem bequeathed to his successors. President Barack Obama did not want to deal with Iraq, but there it was. Trump does not want to deal with Afghanistan or Syria or Iraq, but they are not going away. “Fear” does a great job of describing Trump’s frustration with his national security advice. As Lawrence Freedman noted in his review of the book, “It is interesting to see how the president feels trapped at times. The weight of military and expert advice telling him he has no choice but to stick with Afghanistan pins him down.”

Advocates of restraint are correct to note the unfairness of it all. The decision to not use force can always be reversed. The decision to use force is almost impossible to reverse without even greater costs. This is the conundrum Trump finds himself in on Syria, which might explain how he has gone from saying “we have defeated ISIS” last month, using an alternate term for the Islamic State, to saying, “we will be leaving at a proper pace while at the same time continuing to fight ISIS and doing all else that is prudent and necessary” on Monday. His frustration also casts this otherwise borderline-incoherent tweet in a more sympathetic light:

So far, Trump has refrained from using military force in new theaters. If he follows through on withdrawals from Syria and Afghanistan, is it possible that Trump’s successor will have fewer inherited messes than Trump? No, because ongoing military interventions are not the only kind of bad foreign policy legacy one can leave.

Trump’s lasting foreign policy legacy will be the erosion of America’s ability to credibly commit. On U.S. forces in Syria, Trump has been so all over the map that it has weakened the credibility of his subordinates. As Politico’s Nahal Toosi noted about Secretary of State Mike Pompeo’s scheduled trip to the region, “a question looms larger by the minute: Can foreign leaders believe he speaks for an unpredictable president?” She warns, “The gyrations in the various policy statements are so extreme that critics of the administration say Pompeo can’t claim with confidence to truly speak for the president.”

The problems go well past Trump’s ability to credibly commit; it is whether the United States will be seen as able to credibly commit after Trump leaves the stage. The current president has compensated for his inability to get U.S. forces out of the Middle East with his ability to withdraw the United States from numerous international agreements ranging from the Trans-Pacific Partnership to the Iran nuclear deal to the Universal Postal Union. He has successfully eroded the norm that the United States will stay in international agreements. America could elect the most committed internationalist in 2020, and allies and partners will still be wary of a Trump-like figure returning to the presidency and wreaking havoc again.

I do feel a little sorry for Trump; he seems to want to withdraw U.S. troops but is stuck in situations created by his predecessors. On the other hand, the president has taken a blowtorch to America’s reputation. That will not fade away soon, if ever.