Vladimir Putin’s decision to back Donald Trump’s 2016 presidential campaign increasingly looks like one of his smartest investments. Soon, Putin may join North Korea’s Kim Jong Un in getting the cachet of a summit with the American president.


But what’s good for the Russian autocrat and his willing American enabler will almost certainly be bad for the United States.


In recent weeks, Putin has seen Trump take significant steps to rupture the Atlantic alliance that has been the main Western bulwark against Soviet and Russian adventurism; exacerbate economic tensions with longtime U.S. allies, which will help the Kremlin economically; and signal a U.S. retreat from acting as a military shield for democracies in the Far East — and potentially Europe.


Meanwhile, Trump continues to resist criticizing Russia’s 2016 election interference, even though it was confirmed by U.S. intelligence agencies; is working to undermine the independent counsel’s investigation into whether his campaign encouraged Russian assistance; and has done nothing to prevent renewed Russian interference this year and in 2020.


It’s important to understand that the informal Putin-Trump alliance is no sudden thing but has been decades in the making, starting long before Putin gained and consolidated power and Trump sought and won the presidency. Its roots stem from the 1980s, when real estate developer Trump first foresaw a role in forging a superpower nuclear deal and envisioned extending his real estate empire toward the Soviet Union.


In 1984, Trump said in several interviews that conversations with his uncle, a prominent nuclear physicist, convinced him a U.S.-Soviet deal was necessary to avoid a nuclear holocaust. “It would take an hour and a half to learn everything there is to learn about missiles. … I think I know most of it anyway,” he told The Washington Post.


Last year in an interview with The Hollywood Reporter, Nobel Peace Prize winner Bernard Lown recounted a conversation he had with Trump in 1986. Trump had called after Lown returned from a Moscow meeting with Soviet President Mikhail Gorbachev. Trump suggested he would ask President Ronald Reagan to name him a special envoy to make a nuclear deal with Gorbachev.


“He said he would go to Moscow and he’d sit down with Gorbachev, and then he took his thumb and he hit the desk and he said, ‘And within one hour the Cold War would be over,’” recalled Lown, a physician honored for his antiwar efforts. There is no indication anything like that happened, but Trump’s alleged scenario sounds strikingly like his Singapore summit with Kim.


Trump first visited Moscow in 1987 to study the possibility of building luxury hotels, a recurrent but never consummated goal of many subsequent visits and inquiries, most recently in 2016. Though he never built there, Trump’s 2016 claim that he had “nothing to do with Russia” was certainly misleading, if not flatly inaccurate.


As early as 2008, his son Donald Trump Jr. said, “Russians make up a pretty disproportionate cross-section of a lot of our assets,” adding “we see a lot of money pouring in from Russia.” Over the years, Trump Jr. made numerous trips to Russia, presumably arranging the Russian financing that many have reported Trump got for overseas projects.


So it was hardly surprising that, when Russian interests close to Putin sought to contact Trump’s 2016 campaign, they reached out to his son for that Trump Tower meeting Independent Counsel Robert Mueller is exploring.


What resulted from that and other contacts remains unknown. But during his campaign, Trump sometimes took policy positions reflecting Putin’s interests more than traditional American ones, notably by raising doubts the United States would abide by Article 5 of the NATO treaty, obligating members of the 70-year alliance to aid one another if attacked.


Before last week’s annual G-7 meeting of major industrial nations, Trump floated the idea of re-inviting Russia to rejoin the organization from which it was expelled after it grabbed Crimea from Ukraine in 2014. The other countries rejected that and drafted a conference-ending statement reiterating Western unity on issues such as climate change, trade and the Iran nuclear agreement, which Trump has assailed.


When Canadian Prime Minister Justin Trudeau reiterated Canada’s desire to resist Trump’s tariff increases, the president vowed to persist with the policy, which could drive long-time U.S. allies like Germany into expanded trade with Russia. This week, he assailed Germany’s handling of immigration issues.


And Trump’s unexpected announcement curtailing U.S. military exercises with South Korea — and suggestions of possible U.S. troop withdrawals — signals withdrawal from 75 years of U.S. global leadership that has provided American allies with a protective shield against both Russia and China.


Not all administration officials share the president’s benign view of Russia. “Putin seeks to shatter NATO,” Secretary of Defense James Mattis warned last week. “He aims to diminish the appeal of the Western democratic model and attempts to undermine America’s moral authority.”


But to Trump, Putin remains more friend than foe.


Carl P. Leubsdorf is the former Washington bureau chief of the Dallas Morning News. Readers may write to him via email at: carl.p.leubsdorf@gmail.com.