Defending a democratic Ukraine is crucial to the project of global freedom, he contends, and Putin’s influential brand of illiberalism cannot be confronted on friendly terms. Despite his book’s title, Vindman, a self-described neo-idealist and admirer of Tallis, spends much of “The Folly of Realism” criticizing old-school idealists. The American foreign policy establishment, he writes, must reject “a sentimental faux idealism” that is “comfortable imagining adversaries as potentially cooperative.”

In hindsight, some American leaders did seem overly effusive about the prospect of bringing Putin into the fold. In 2001, President George W. Bush notoriously said that looking into Putin’s eyes gave him a sense of his soul, finding the Russian leader “very straightforward and trustworthy.”

President Clinton, in his 2004 autobiography “My Life,” concluded that more than a billion dollars in American aid to dismantle nuclear weapons, among other objectives, was a lot cheaper than a Cold War rerun. Plus, Clinton recalled, “Putin was compact and extremely fit from years of martial arts practice,” suggesting that the new Russian president was tough enough to manage the country’s “turbulent political and economic life.”

The United States Agency for International Development, which the Trump administration is busy dismantling, was a main vehicle for funneling American help to Russia. But this support began to crater after Russia’s financial crisis in 1998, a time when many impoverished Russians began to sour on democratic reforms.

Washington considered one of the most important developments during those years to be the departure of two trains from Ukraine to Russia on May 31, 1996, carrying away the last of the country’s strategic nuclear warheads. This move was part of a treaty signed with the promise of security guarantees from Russia, the United States, Britain and, later, China and France.