"Negotiations are on track! President Trump @POTUS & @Prezydentpl (Andrzej) Duda's vision for increased US presence in Poland will be even greater than originally outlined. Announcement coming soon," US Ambassador Georgette Mosbacher said in a Thursday tweet.

A country of 38 million people on NATO's eastern flank, Poland has long campaigned for a permanent US troop presence on its soil to ward off Russian adventurism.

Conservative Polish President Andrzej Duda has tried to charm the US president, even pitching the idea of Poland building a "Fort Trump" to house thousands of US soldiers.

Poland's Prime Minister Mateusz Morawiecki said on Saturday that his country hopes to welcome larger US troop rotations after the Wall Street Journal reported that Washington plans to slash its military presence in Germany.

Talks on the possibility "are ongoing", Morawiecki said.

The WSJ quoted unnamed sources saying that US President Donald Trump had ordered the Pentagon to cut the number of military personnel in Germany by 9,500 from the current 34,500 permanently assigned there.

White House and Pentagon officials declined to confirm or deny the WSJ story, which comes amid tensions between the Trump administration and European allies over longstanding cooperation agreements.

Poland has long regarded the United States as the primary guarantor of its security within the NATO Western defence alliance, which Warsaw joined in 1999, a decade after it broke free from the crumbling Soviet bloc.

US President Donald Trump has already upped his country's troop rotations in Poland to 5,500 personnel as part of a wider NATO response to concerns in the region triggered by Russia's 2014 annexation of territory from neighbouring Ukraine.

Thousands of US and Polish troops are currently engaged in the June 5-19 Defender-Europe 20 manoeuvres, the first large-scale war games in Europe since the coronavirus pandemic struck the continent.

Testing, quarantines and social distancing are part of the drill for the more than 6,000 troops, including Poles and 4,000 Americans, at the Drawsko Pomorskie military training range in northern Poland.