The Soviet Union, which collapsed 25 years ago on Christmas Day, united the American political establishment for decades, generating a unanimous view that Moscow represented the primary threat to the U.S.

Today’s Russia is having the opposite effect, dividing many Republicans and Democrats and illustrating the larger breakdown of a national consensus on major foreign policy questions.

Throughout the Cold War, the U.S. approach toward the Soviet Union, and international relations in general, was encapsulated in 1948 by Republican Sen. Arthur Vandenberg: “We must stop politics at the water’s edge.”

Yet Republicans and Democrats are now waging a fierce battle over precisely what role Russia played in the U.S. election and how Donald Trump’s incoming administration should deal with Russian President Vladimir Putin.

Both U.S. parties have shown extreme flexibility in recent years, with each labeling Russia a serious — or not-so-serious — threat, depending on their short-term domestic political agendas.

In the 2012 presidential election, Republican nominee Mitt Romney described Russia as “our No. 1 geopolitical foe.” He called President Obama naive for his failed attempt to reset relations with Russia, a country that “lines up with the world’s worst actors.”

Obama responded by mocking Romney with this zinger in a presidential debate: “The 1980s are now calling to ask for their foreign policy back because the Cold War’s been over for 20 years.”

That was one of the more memorable lines of the campaign. But Russia’s been extremely busy since then, with Putin annexing Crimea in 2014, backing separatists in Ukraine and launching a bombing campaign that has significantly strengthened Syrian President Bashar Assad. Republicans have repeatedly decried Obama’s response as far too tepid.

Reversing positions this year

In the wake of the 2016 presidential elections, party leaders have largely reversed positions. Based on the findings of the CIA and other intelligence agencies, many Democrats are outraged over what they say was Russia’s effort to tip the election in favor of Republican Donald…