Cohen was a contributing editor to The Nation magazine, published and partially owned by his wife Katrina vanden Heuvel.

[citation needed] While on an undergraduate study abroad program in England, he took a four-week trip to the Soviet Union, where he became interested in its history and politics.

[4][5] In his first book, Bukharin and the Bolshevik Revolution, a biography of Nikolai Bukharin, a leading Bolshevik official and editor of Pravda, the official newspaper of the Communist Party of the Soviet Union, Cohen argued that Communism in the Soviet Union could have easily taken a different direction, not leading to Joseph Stalin's dictatorship and purges.

[13] According to Eugene Huskey, William R. Kenan chair at Stetson University, in the 1970s Cohen viewed the Soviet Union as "simply inefficient and corrupt" rather than a totalitarian state.

[14] In an article for The Nation, published in the March 3, 2014 issue, Cohen wrote that "media malpractice" had resulted in the "relentless demonization of Putin" who was not an "autocrat".

[15] In a follow-up interview with Newsweek magazine, Cohen said Putin was the "best potential partner we had anywhere in the world to pursue our national security".

[17] In a May 2014 Nation column coauthored with his wife, Cohen wrote that President Barack Obama had unilaterally declared a new Cold War against Russia and that those inside the Beltway were complicit in it by their silence.

[20][1] Cohen participated in a Munk Debate in Toronto, Ontario, Canada in April 2015, on the proposal "Be it resolved the West should engage not isolate Russia."

He stated that a military alliance that President Obama had tried to establish with Putin against terrorism was "sabotaged by the Department of Defense and its allies in the intelligence services".

[16] In a June 30, 2014 article in The Nation, Cohen said the US was complicit in creating the crisis in Ukraine due to its support for the overthrow of President Viktor Yanukovych.

He criticized the US political-media establishment for being silent about "Kiev's atrocities" in the Donbas region which is heavily populated by Russian-speaking Ukrainians and ethnic Russians.

[26] In 2014, Cohen disputed evidence that Russia shot down Malaysia Airlines Flight 17, an event that killed all 298 passengers and crew.

He said the Ukrainian government had possession of Russian Buk surface-to-air missiles, and suggested the country "was playing with its new toys and made a big mistake.

[28][29][30][31][32] In a 2014 article in The Nation, Cohen wrote that "the US-picked prime minister, Arseniy Yatsenyuk, referred to resisters in the Southeast as 'subhumans'.

"[16] Historian Timothy Snyder disagreed with Cohen's statement, writing that Yatsenyuk, in a message of condolence to families of killed Ukrainian soldiers, described the attackers as "inhuman".

Snyder suggested that the origin of Cohen's statement was Russian media mistranslation of neliudy ("inhuman") as nedocheloveki ("subhuman").

[46][47] Also in 2015, Cohen with Gilbert Doctorow and others reestablished the American Committee for East–West Accord, which describes itself as a pro détente advocacy group.