During the 2016 presidential election cycle, there was a largely partisan effort to portray Donald Trump and his advisors as being under undue Russian influence. Now that campaign has turned into something much broader, uglier, and more dangerous. It has become a crusade to make Russia a pariah and impugn the loyalty and ethics of anyone who advocates even a modestly less confrontational relationship with that country.

The latest salvo in that campaign is a May 15 Washington Post story charging that President Trump revealed highly classified information to two Russian officials, Foreign Minister Sergey Lavrov, and Moscow’s ambassador to the United States, Sergey Kislyak, during a meeting at the White House. The clear implication was that this alleged sharing of intelligence data was highly improper, if not treasonous.

National Security Advisor H. R. McMaster and other officials flatly denied that any information regarding intelligence sources and methods was given to the Russians. Even if Trump had done so, he violated no laws. It has been well established for decades that the president can instantly declassify any materials and share them with any individual he chooses. Since the information in question apparently involved ISIS terror plans, including using computer laptops to smuggle bombs on board commercial aircraft, it would not be surprising if the administration was willing to share its knowledge with Russian officials. Russia has been the victim of Islamic terrorist attacks on several occasions and is a de facto ally in the war against ISIS.

The underlying message in the Washington Post story—and the subsequent comments by prominent Democrats and their allies in the media—is that close cooperation with Moscow, even on anti-terrorism measures, is illegitimate. That is merely the latest stage in an intensifying anti-Russia hysteria. Russophobes have portrayed not only Trump and his associates, but scholars and journalists who have no affiliation with the administration, as “Putin puppets” if they dare favor anything less than an ultra-hardline policy toward that country. Victims of such smears include Princeton Professor Stephen Cohen, a longtime distinguished scholar on the Soviet Union and Russia, the Intercept’s Glenn Greenwald, syndicated columnist Pat Buchanan, former Republican congressman and presidential candidate Ron Paul, and TAC columnist Daniel Larison.

Such tactics echo the worst excesses of the McCarthy era in the 1950s and threaten to poison the public discourse. They also risk applying to Russia what has been an especially counterproductive feature of U.S. foreign policy over the decades. Often in response to public and congressional pressure, American leaders have attempted to make designated governments diplomatic and economic pariahs. Washington refused to have any direct dealings with Communist China from 1949 until Henry Kissinger and Richard Nixon abandoned that strategy in the early 1970s. A similar approach was in effect regarding Cuba from 1960 until President Obama began to normalize ties in 2014. An isolation strategy existed toward Vietnam for more than 20 years following the communist conquest of South Vietnam in 1975. Until a very limited rapprochement occurred over the past two years, the same state of affairs existed with respect to Iran. And there is only the occasional glimmer of a beneficial policy shift regarding the decades-long campaign of isolation against North Korea.

All of those isolation policies had one feature in common: They were miserable failures. In some cases the results were merely frustrating and disappointing—as with Cuba, Iran, and Vietnam. Using that strategy toward China was disastrous, however, leading to a bloody clash during the Korean War, two instances of nearly stumbling into war over Taiwan, and the U.S. pondering an attack to eliminate Beijing’s embryonic nuclear program in the mid-1960s. The current ominous tensions regarding North Korea indicate that the policy could produce equally unfortunate results there, perhaps even triggering a second Korean War.

Given that dismal track record, an attempt to make Russia a pariah would be the essence of folly. Not only is Russian cooperation valuable in addressing a number of mutual problems, including Islamic terrorism and defusing the North Korea crisis, but Russia remains an important player overall in the international system. Being on bad terms with—much less trying to isolate—a power that possesses several thousand nuclear warheads is criminally reckless. The current anti-Russia hysteria is not only extremely damaging to America’s internal political health; it also could produce catastrophic international consequences.

Ted Galen Carpenter, a senior fellow in defense and foreign policy studies at the Cato Institute, is the author of 10 books, the contributing editor of 10 books, and the author of more than 650 articles on international affairs.