A top general announced Thursday that President Joe Biden had authorized the military’s call-up of 3,000 reserves to support operations across Europe, after tens and thousands of troops were deployed there last year following Russia’s invasion.

The move indicates that active duty forces have been stretched by the U.S. Military’s training mission to Europe and the deployment of new brigades following the invasion.

The director of operations of the Joint Staff told reporters Thursday that the decision reaffirmed the commitment and support for NATO’s east flank, in light of Russia’s unprovoked and illegal war against Ukraine.

The move will give the European Command of the U.S. military “greater flexibility” in defending the continent. However, the actual levels of force in Europe will not be affected, according to Capt. Bill Speaks is a spokesperson of the U.S. European Command.

The order designates Operation Atlantic Resolve – the U.S. effort to defend Europe – as a contingency operations for the first. This allows the Pentagon the authority to quickly acquire equipment and call up reserves.

This designation allows the President to mobilize Reserves and ensures that they are paid as active duty troops. The designation also ensures that the families and dependents are supported if a reservist is deployed.

After Russia’s invasion of Europe, the U.S. sent 20,000 additional troops to the continent. This brings the total number to more than 100,000. This includes new rotations in Poland of 10,000 troops, which has become a crucial hub for supporting and providing Ukraine.

Potential call-ups follow the NATO summit held in Lithuania last week, when allies committed to have 300,000 troops prepared for rapid deployment in 30 days or less. The 31-member NATO alliance faces a daunting task after years of underfunding their military.

Ukraine is also continuing to attack Russia’s main defense lines in Donetsk, and Zaporizhzhia. Senior Pentagon officials have expressed hope that Kyiv will soon recapture significant territory, but they claim progress has not been as rapid as hoped.

Sims announced on Thursday that new American cluster bombs had arrived in Ukraine after the Pentagon made the controversial decision last week to send them. Sims said on Thursday that the Pentagon announced the controversial decision to send them last week.