WASHINGTON — The United States plans to carry out small ground-force exercises in Poland and Estonia in an attempt to reassure NATO’s Eastern European members worried about Russia’s military operations in and near Ukraine, Western officials said Friday.

The moves are part of a broader effort by NATO to strengthen the alliance’s air, sea and land presence in Eastern Europe in response to Russia’s new assertiveness in the region.

It is not yet clear what additional troop deployments the United States and other NATO nations might undertake in Eastern Europe after the exercises and to what extent the moves would ease anxieties there.

The land-force exercises the Obama administration is planning are extremely modest.

The exercise in Poland, which is expected to be announced next week, would involve a United States Army company and would last about two weeks, officials said. A company consists of about 150 soldiers.