The US will launch more than 1,000 troopers in Poland, President Donald Trump said in a press conference with Polish President Andrzej Duda.
President Trump said that the force would be taken from the 52,000 American strong contingent in Germany, and with
However, he fell into making a permanent US base in the country.
It came after Warsaw's offer to spend $ 2bn (£ 1.57bn) on building one.
] The base may be called Fort Trump, President Duda told his visit to the White House on Wednesday.
President Trump said America is " very interested "in the idea, but reluctant to work in a permanent facility – something that is likely to motivate Russia's response.
"I do not mention about being permanently or not permanently," he told reporters, adding that the base "is definitely a statement".
Visit – the second Mr. Duda in less than a year – celebrates the 20th anniversary of Poland's membership in Nato, and the 30th anniversary of the collapse of communism in the country.
Speaking to reporters, Mr Duda thanked Mr. Trump for his "great kindness towards Poland and perfect understanding of Polish matters."
After leaving Washington, the Polish president scheduled to visit Texas, Nevada and California for energy and technology talks
In recent years the Warsaw government has been launching Americans to establish a permanent military base in Poland to host up to a division (several thousand) American troops.
The idea is quickly called "Fort Trump". But there are problems.
Who will pay? Up to $ 2bn is offered by Warsaw, but it covers only the initial establishment of the base.
Where did the troops come from? Moving them a lock of stock and barrel from the US is hugely expensive; Transferring some from Germany or Italy may damage the alliance of the alliance.
Above all, a permanent base could spoil the 1997 agreement between Nato and Russia.
What happened was a fudge. Fewer troops than requested, and again on a perimeter basis. It is seen by US commanders in strengthening readiness.
But these rotational groups will help to build Poland's military infrastructure to receive more soldiers as needed in the future.
What was the agreement between the US and Poland?
Both leaders signed a joint declaration confirming the cooperation of defense countries.
This agreement includes provisions for Poland to provide "bases and infrastructure for 1,000 American troops", temporarily placed on a perimeter basis.
However, when the reporters asked later, Trump said "they are talking about 2,000 troops."
Speaking to the BBC, an official from the US The Department of Defense has not proven how many personnel mailed to Poland under the new agreement.
It is also unclear who will be talking about the cost of the latest US expansion.