"NATO's not talking about establishing bases... We support an enhanced presence, but we can do it without bases, bases, bases," James Townsend, a senior Pentagon official, said in Bratislava on Friday, EUobserver reports.
Townsend was speaking at the GLOBSEC conference in Slovakia and was responding to Polish Foreign Minister Witold Waszczykowski's calls for "presence, presence, presence" of NATO troops in Eastern Europe in order to deter Russia.
German Defence Minister Ursula von der Layen had previously said that NATO would deter Russia with rapid response units rather than new permanent bases in countries like Poland.
She said rapid response forces are more than enough to prevent Russia from considering an attack on Poland or the Baltic states.
Last February, NATO defence ministers decided to back "permanent rotation" of NATO forces in Eastern Europe rather than permanent bases.
NATO's rapid response units will include some 4,000 US troops deployed to the Baltics for several months at a time.
Ahead of the NATO summit in Warsaw this July, Poland and the Baltic States have been calling for more reassurance measures in Eastern Europe.