The Russian government’s recent announcement of its decision to eject American diplomats and block access to two  diplomatic properties may signal an approaching tipping point in the United States-Russia relationship. Trump administration officials and members of Congress should consider very carefully how to proceed.

While the Russian Foreign Ministry’s official announcement of Moscow’s latest moves focused primarily on Russia’s complaints about a new sanctions bill approved by Congress, Russia’s actions appeared to be a belated tit-for-tat response to the Obama administration’s expulsion of 35 Russian diplomats and seizure of two diplomatic compounds over Russia’s alleged interference in the 2016 presidential election. Importantly, the Foreign Ministry statement explicitly noted that Russia’s government reserved the right to impose further measures in response to any U.S. steps. This was a clear warning to the U.S., and it followed increasingly impatient Russian demands that Washington return the two properties taken late last year.

The most immediate question for the administration is whether and when President Donald Trump will sign the latest sanctions into law, something that seems likely to happen soon.  Separately, the U.S. is  reportedly considering providing lethal defensive weapons to Ukraine, as well as longer-term measures to retaliate for Russia’s suspected election-related hacking initiated by the Obama administration. There’s been no indication so far that Trump has put implementation of these measures on hold. For its part, Moscow will also have to decide whether to respond further if Trump signs the sanctions legislation. Moscow has many options in responding to an announcement that the U.S. will arm Ukraine or to covert American cyber actions against Russia. In combination, these processes could easily accelerate a dangerous escalatory spiral.

Rapid escalation of the U.S.-Russia confrontation could be shocking for many Americans, including policymakers, members of Congress and journalists, among others. Indeed, while many have come to agree with the view offered by 2012 Republican presidential candidate Mitt Romney, that Russia is America’s “number one geopolitical foe,” few seem to remember what it truly means to face a powerful enemy state. This is in part because since the Cold War, America has generally chosen to confront only weak to middling states, such as Iran, Iraq, Libya and North Korea. It is also in part because the U.S. media has tended to conflate refusal to cooperate with active opposition to U.S. objectives.

In practice, however, there is a big difference between failing to cooperate and pursuing energetic resistance to the U.S. It is the difference between refusing to pressure eastern Ukrainian rebels to give in to Kiev and directly invading and seizing a large portion of Ukraine. Or between vetoing additional sanctions on North Korea and offering economic and military assistance to Pyongyang. Or between disagreeing over who is a terrorist and providing weapons, money and other help to terrorist organizations targeting Americans. If Moscow’s foreign policy reaches and passes the tipping point between the former of these behaviors and the latter, Russia could seriously harm U.S. national security interests in ways Americans have not experienced for decades.

From a historical perspective, the present period has something in common with both the 1950s, when the Red Scare spurred a search for enemies within, and the 1980s, when late Cold War tensions peaked. Yet today’s tensions are also quite different in that the Cold War Soviet Union was already a demonstrably hostile power. Russia has not yet irreversibly crossed this threshold. In fact, in some ways the current situation is like a reverse version of the late 1980s, when the Soviet Union gradually stopped working against U.S. interests and Americans gradually stopped considering the U.S.S.R. to be an enemy. We may soon cross this invisible line in the opposite direction.

For more than 20 years, U.S. policymakers have enjoyed the luxury of formulating American foreign policy with few constraints and often with only cursory evaluation of how others may respond to Washington’s decisions. The U.S. was the world’s only superpower—a nation that none dared challenge head-on and that few deliberately angered. If Washington and Moscow enter a real confrontation—beyond the recent spasmodic bouts of mutual frustration—America’s policy elites may find that their earlier dismissive attitudes toward Russia’s perspectives and capabilities will prove quite costly. Alternatively, policymakers could take a hard look at U.S.-Russia relations before reaching that point and try to find a way out of this mess.

Paul Saunders is the executive director of the Center for the National Interest. 

The opinions expressed in this blog post are solely those of the author.