From the Daily Mail
The 60,000 US troops already based in Europe that Biden can use to defend Ukraine against Russia: President orders extra 8,500 US-based troops to be on standby to deploy and places
Nearly 64,000 U.S. troops stationed in Europe could be deployed to the continent’s eastern flank if President Biden makes such a call to counter growing Russian aggression at the border with Ukraine.
The USS Harry S. Truman has already been placed under NATO command for the first time since the end of the Cold War, while 40 warships, 175 aircraft and 90 tanks situated throughout Europe could also be readied for conflict.
Biden has ordered 8,500 U.S.-based troops to stand ready to deploy to Eastern Europe, while military officials have presented him with a plan to send 50,000 more if the security situation deteriorates and Russia launches an invasion into Ukraine.
[T]he U.S. had about 175,000 troops stationed abroad as of September 2021. A total of nearly 64,000 of those service members were stationed in Europe.
Command for the U.S.’s 40 warships is based out Italy, and the U.S. has already flexed its muscle to Russia by sending ships to the politically fraught Black Sea.
Germany houses the largest deployment of U.S. troops in Europe, and only Japan and America have more U.S. troops based there. There are 35,468 U.S. troops in Germany – 21,585 Army, 13,009 Air Force and small numbers of troops from the Marine Corps and Navy.
There are 21 U.S. military bases across Germany, with the largest presence at Stuttgart, headquarters of United States European Command (EUCOM) and US Africa Command, and Ramstein, headquarters of US Air Force operations in Europe.
Ukraine shares a border with four NATO countries: Poland, Slovakia, Hungary and Romania.
Italy has the second highest U.S. presence in Europe, with 12,436 troops, 4,081 belonging to the Army, 4,742 Air Force and 3,497 Navy. The Naples port is the headquarters of the Sixth Fleet, or US Naval Forces Europe-Africa.
The Aviano Air Base is home to two U.S. F-16 fighter jet squadrons. The F-16 is a popular air-to-air combat jet used by 25 air forces.
In the United Kingdom there are 9,576 U.S. troops, almost entirely members of the Air Force with small numbers of service members from other branches.
Spain has 3,423 U.S. troops stationed there, Belgium has 1,143, Greece has 429, Portugal has 259, and Romania has 132. A handful of other nations have a U.S. troop presence smaller than 100.
There are also currently more than 150 U.S. military advisers in Ukraine who have operated at a training ground near Lviv for years. It includes Special Operations forces, mostly Army Green Berets, and National Guard trainers from Florida’s 53rd Infantry Brigade Combat Team.