U.S. European Command is already cutting back on its plans for the large-scale combat exercise on the continent that kicks off this spring.

The decision was made to curtail the exercise in order to deal with the spread of the novel form of coronavirus, also known as COVID-19, that already forced the U.S. Army Europe commander to self-quarantine himself earlier this week.

“After careful review of the ongoing Defender-Europe 20 exercise activities and in light of the current coronavirus outbreak, we will modify the exercise by reducing the number of U.S. participants,” EUCOM officials said in a press release. “Activities associated with the exercise will be adjusted accordingly and we’ll work closely with Allies and partners to meet our highest priority training objectives.”

The exercise mostly involves Army personnel, including roughly 20,000 U.S. soldiers who were supposed to deploy from the continental United States to support activities across 10 European countries. The major participating units include soldiers from the 1st Cavalry Division, 1st Armored Division, 1st Infantry Division, 3rd Infantry Division and 82nd Airborne Division

Army spokeswoman Lt. Col. Robin Ochoa deferred to EUCOM leadership regarding what units and how many participants were being reduced. Those details have yet to be released by the command, however.

“As we work through the arrangements with our Allies and partners, we’ll provide additional updates,” EUCOM officials said in the release.

Gear has already been trickling onto the continent at select ports. Equipment belonging to the 2nd Brigade Combat Team, 3rd Infantry Division was rolling off ships at the port of Bremerhaven, Germany, on Feb. 20, as part of the opening salvo of the largest deployment of soldiers from mainland United States to Europe in a quarter century.

EUCOM officials did not say in their release what the reduction will look like, but the virus’ spread also forced the command and their Norwegian allies to cancel the large scale Arctic exercises known as Cold Response.

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That exercise included roughly 15,000 troops from the U.S., Norway and eight other allied countries. Roughly 1,500 U.S. troops were scheduled to participate in the Arctic exercise from all four service branches.

“We take the coronavirus outbreak seriously and are confident that by making this important decision we’ll continue to do our part to prevent the further spread of the virus, while still maximizing our efforts to advance our alliances and partnerships and enhancing our comprehensive readiness to address any crisis or contingency,” the EUCOM release reads.