A reported decision by President Trump to remove some 9,500 American troops from Germany could undercut a half decade long effort to prevent war by enhancing NATO’s deterrent posture in the Baltic area. The prospect of a withdrawal came without warning to American commanders in Europe and has no known strategic underpinning.

NATO has been clear about the Russian threat and how to counter it. During the 2018 Brussels summit, NATO leaders concluded that “Russia’s aggressive actions, including the threat and use of force to attain political goals, challenge the Alliance and are undermining Euro-Atlantic security and the rules-based international order.” NATO’s response has been to construct a deterrent posture with several thousand NATO troops forward deployed in the Baltic states and Poland as a solid trip wire and with ready reserves further back poised for quick reinforcement should the trip wire fail.

This deterrent posture is already fragile. There are doubts that the NATO Response Force and other national forces are adequately ready and that the logistics infrastructure is capable of enabling the rapid forward movement of troops. To deal with this fragility, NATO adopted two initiatives on readiness and mobility to assure that reserve forces would arrive in time.

All of this has been constructed to deal with what U.S. commanders in Europe have called their nightmare scenario. They fear a quick Russian land grab in the Baltic states followed by Russian propaganda, a Russian call for a cease fire, and a nuclear threat are all designed to divide NATO in time of crisis and make it impotent.

If this scenario is not adequately countered, NATO leaders fear Russia might take the gamble as they have gambled in Ukraine, Georgia, Syria, and now Libya. U.S. Russian experts note that President Vladimir Putin may take risky foreign policy steps to counter the growing COVID-19 crisis in Russia. Russia just announced the forward deployment of a motorized brigade to the Western Military District bordering the Baltic States. This is not the time to remove American troops.

So how would a withdrawal decision undercut NATO’s strategy to deter the nightmare scenario?

The U.S. forces most likely to be cut are F-16s and support troops in Germany. They are both crucial to NATO’s reinforcement strategy. Support forces are needed for training and as part of the mobility effort to move NATO troops forward in time of crisis. American air power is needed since it is able to launch strikes quickly in support of forward forces while other ground forces, both American and European, mobilize and move forward. Without these 9,500 troops, Poland and the Baltic states will be more vulnerable, along with the American personnel that remain.

But the problem goes deeper. A withdrawal would be a clear signal that Trump is not serious about defending Europe. It would undercut the very deterrent strategy that both the Obama and Trump administrations have put in place to contain an aggressive Russia. It further undermines European confidence that America has Europe’s back. European powers may think twice before extending the deployment of their now more vulnerable forward deployed troops, further reducing deterrence.

Plus the flawed decision could lead to the demise of the NATO Readiness Initiative and the Mobility Initiative, both of which the United States pressed hard for and Europe has supported. If the United States undercuts the reinforcement strategy that underpins these two initiatives, why would Europe have faith in them?

This decision would compound the damage done to transatlantic security by earlier Trump decisions. For example, Trump’s withdrawal from the INF mid-range nuclear agreement — rather than fixing it — now gives Russia a significant and legal nuclear advantage over NATO’s nuclear deterrent on the continent. So if that nightmare scenario takes place, NATO will be less well prepared to deal with a nuclear threat, again tempting the Kremlin to take the risk.

All is not lost. Both houses of Congress have shown strong support for the NATO alliance in face of continuous Trump assaults and should pass legislation aimed at overturning such an unwise decision.

Hans Binnendijk is a distinguished fellow at the Atlantic Council. He has served two tours on the National Security Council and as director of the Institute for National Strategic Studies. He has worked on NATO issues for four decades.