In his timely new book, “The Folly and the Glory: America, Russia, and Political Warfare 1945-2020,” Tim Weiner guides us briskly through 75 years of mistrust and machinations between Moscow and Washington, setting Vladimir Putin’s offensive against our democracy in context. A veteran tiller in the field of national security, Weiner offers a well-written and provocative journey to this era’s perilous fight.

Reflecting current concerns about Moscow’s use of social media and foreign allies to widen our internal political, social and cultural divisions, Weiner focuses on the central role that political warfare has long played in the contest between the United States and Russia. Defined in 1948 as “the employment of all the means at a nation’s command, short of war, to achieve its national objectives,” political warfare was the weapon of choice for both sides that helped keep the war cold rather than hot. And Weiner is especially adept at unearthing and explaining the covert side of it all.

The United States engaged in ad hoc political warfare as far back as the early days of the republic. But the Truman administration became the first U.S. government to institutionalize the practice, in the 1940s, amid mounting evidence that Soviet leader Joseph Stalin sought to dominate Europe. The Soviets were already engaging in political warfare throughout the continent, aided by the presence of the Red Army in the East and by communists and their supporters, open and concealed, in Western Europe. In June 1948, the National Security Council issued a directive that formally assigned responsibility for “covert operations” in peacetime to the recently established Central Intelligence Agency and authorized the creation of a special unit within the CIA to run these activities.

Picking up on a theme of his National Book Award-winning history of the CIA, “Legacy of Ashes,” Weiner highlights the self-defeating hubris that often accompanied the use of this weapon. A gifted storyteller, he creates memorable portraits of the players. The State Department’s George Kennan, the first significant voice on American national security in the Cold War, sparked the National Security Council’s adoption of political warfare. In May 1948, “Kennan delivered a manifesto,” Weiner writes, that was titled “The inauguration of organized political warfare.” It was so explosive, “crucial paragraphs . . . remain classified top secret today.”

Weiner, who won the Pulitzer Prize for national reporting in 1988, renders a mixed verdict on the American deployment of the dark arts in the struggle with Moscow. In his telling, the efforts were sometimes successful and other times disastrous, often resulting in a range of unintended consequences. His page-turning account of U.S. complicity in creating Joseph Mobutu’s kleptocracy in Congo is a reminder of how policies can succeed on one level and fail on another. Backed by the CIA, Mobutu became a reliable anti-communist who then exploited his position to pillage his country.

Another covert action described in marvelous detail is the U.S. role in assisting Pope John Paul II and the forces of freedom to undermine Soviet rule in Poland. Amid Lech Walesa’s Solidarity movement, President Ronald Reagan met with the pope in June 1982. “Both men had survived assassination attempts the year before, six weeks apart,” Weiner writes. “Reagan believed that they had a mystical bond, that they had been spared death for a divine purpose.” In the absence of an official record of the meeting, Weiner quotes Thomas P. Melady, who later became U.S. ambassador to the Holy See: “The President brought up to the Pope that he had read that the Pope had said that one day Eastern Europe will be free, and Eastern Europe will join with Western Europe. And President Reagan said, ‘Your Holiness, when will that be?’ And the Pope said, ‘In our lifetime.’ The President sort of jumped out of his chair and . . . grabbed his hand and said, ‘Let’s work together.’ ” Five months later Reagan authorized a covert program to liberate Poland, the CIA’s $20 million operation code-named QR/HELPFUL, which included giving Solidarity “sophisticated printing and broadcasting capabilities.” Ultimately, it was the citizens of Poland, led by Solidarity, who defeated the Soviet Union’s repression and its accomplices, but the United States and the Vatican put a heavy finger on the scale.

Although Weiner doesn’t discount the reality of Soviet global ambition or the ultimate incompetence of Cold War Moscow, the book’s treatment of the Soviets’ political warfare lacks the depth of insight and analysis that brings the American sections to life. This changes, however, when Weiner enters the Putin era — his literary juices start flowing and the book gets turbocharged. None of what Weiner says about Putin’s use of political warfare against the United States is new to close followers of the investigative fallout from 2016, or to readers of another important new book, David Shimer’s “Rigged: America, Russia, and One Hundred Years of Covert Electoral Interference.” But as a summation, “The Folly and the Glory” is brilliant. Weiner puts us inside a revanchist Kremlin, angry at its lost empire and happy to make Americans pay for it.

Weiner shows Putin skillfully using cyber and information warfare against Estonia, Georgia and Ukraine before focusing on the United States. Candidate Trump was a gift to Moscow. So, too, were the political vulnerabilities of former secretary of state Hillary Clinton, whom Putin long despised for defending a sovereign Ukraine. With Trump’s victory, Weiner argues, “Putin had pulled off the most audacious political warfare operation since the Greeks pushed a gigantic wooden horse up to the gates of Troy.” And once in the White House, by routinely denying the very existence of Putin’s political warfare against the United States, “Trump would prove to be a priceless asset for the Russians’ war on democracy and the rule of law.”

The book leaves us with a sobering question: Why are the Russians more successful at messing with us now than at any time since the dawn of the Cold War? The Kremlin, after all, is a shadow of its former self. We aren’t facing the existential threat we did from the 1950s through the 1980s. In part, the answer lies in the unprecedented malleability of information and the ease with which false trust can be created in the social media age. But the answer also involves us. The Cold War provided ample evidence that successful political warfare exploits social cleavages and resentments in its targets. Less blinkered by ideology, the new Russians certainly understand our society a lot better than the Soviets did. But there is no escaping that we Americans are arguably as vulnerable to psychological warfare as we have ever been since 1948. The Trump phenomenon, which the Russians abetted but did not create, emerged from a broken nation. Figuring out what we can do about that vulnerability is the most important national security question confronting us today, whether Joe Biden wins or not.

The Folly and the Glory

America, Russia, and Political Warfare

By Tim Weiner

325 pp. $29.99