Between now and September 2020, 1,500 additional soldiers will join the 33,000 US troops in Germany.
The deployment will include a field artillery brigade headquarters and two multiple launch rocket system battalions in Grafenwöhr, near Nuremberg, a short-range air defense battalion in Ansbach, and various supporting units in nearby Hohenfels.
Outside Bavaria, supporting units will also be sent to Baumholder, west of Heidelberg.
The US Army's European headquarters in, near Frankfurt, said the new troops would be permanently stationed as "a display of our continued commitment to NATO and our collective resolve to support European security."
"The addition of these forces increases US Army readiness in Europe and ensures we are better able to respond to any crisis."
Ambassador Grenell said: "Americans are committed to strengthening the transatlantic alliance and President Trump's promise to increase US defense capabilities means the alliance is stronger today."
German Defense Minister Ursula von der Leyen said: "The US decision to increase the military presence here in Germany is a welcome sign of the vitality of the transatlantic relationship and a commitment to our joint security," she said.
US President Donald Trump has repeatedly criticized Germany in particular for, in his eyes, not contributing enough militarily to the defense of Europe. He has repeatedly raised questions about US commitment to the alliance, but would seem to signal a commitment to US involvement in the defense of Europe.
Meanwhile: Fellow NATO member the UK has prepared to withdraw 350 troops from Paderborn, east of Dortmund, reducing its deployment in Germany by about 10 percent.