WARSAW, Poland (AP) — Canada is sending more soldiers than initially planned to a military exercise in Eastern Europe, the country's prime minister said Wednesday, in response to Russia's recent actions in Ukraine.

Stephen Harper's office said Canada plans to send 75 more soldiers to Latvia this month to participate in Saber Strike 2014, a U.S.-led exercise. Those are in addition to 45 Canadians who were already due to take part in the exercise in Poland.

The Canadians are joining about 2,000 other troops from nine NATO countries for the exercises, which take place June 9-21 in Poland, Latvia, Estonia and Lithuania.

Harper's announcement in Warsaw came a day after President Barack Obama pledged to boost U.S. military deployments and exercises throughout Europe.

Both leaders were in the Polish capital to celebrate the 25th anniversary of the first partly free elections in Poland that led to the end of communism.

"I do believe that what is occurring in Russia under President Putin is a serious development with serious long-term consequences that I don't believe we should think for a moment will disappear in the near future," Harper said.

Harper said he was encouraged by Obama's decision to ask Congress for $1 billion to fund the additional U.S. military presence in Europe. Harper said Canada was also "looking at options for additional presence going forward but no decisions have yet been taken."

Polish Prime Minister Donald Tusk, speaking alongside Harper, praised the new American and Canadian commitments. He called on NATO to establish a greater presence in Eastern Europe.

"Why should there be many more NATO troops in Italy than in Poland? Italy borders France and Germany and Austria and Switzerland. Do we expect something bad from those countries? The question is of course rhetorical," Tusk said. "Poland borders Ukraine, Belarus and Russia."

Harper said he could understand the Polish anxieties.

"Whenever a major power attacks and swallows up part of a neighboring country ... this is a threat to the wider neighborhood, so we do share the concerns of people in this country," Harper said.