BERLIN — The United States will increase its military presence in Germany by about 500 personnel to better defend Europe, Defense Secretary Lloyd J. Austin III said during a visit to the country on Tuesday.

The statement not only reverses the previous administration’s plans to withdraw up to 12,000 of the roughly 36,000 U.S. troops stationed in Germany. It also expands the U.S. footprint at a time when Europe is growing uneasy over Russian troop movements near the border with Ukraine.

“These forces will strengthen deterrence and defense in Europe,” Mr. Austin said after meeting his German counterpart, Annegret Kramp-Karrenbauer. “They will augment our existing abilities to prevent conflict and, if necessary, fight and win.”

He did not elaborate on the added troops’ specific mission, saying only that the change would “create more space, more cyber and more electronic warfare capabilities in Europe.”

The new contingent will be stationed in Wiesbaden, home to one of the U.S. military’s most modern installations in Germany. It is the headquarters of the U.S. Army Europe and about 3,000 troops and their families.

The change “will greatly improve our ability to surge forces at a moment’s notice to defend our allies,” Mr. Austin said.