"The (Vladimir) Putin regime's persistent military aggression and its ongoing illegal occupation of Crimea and other parts of Ukraine threaten the stability and security of central and eastern Europe," he said in London, Ont.
The NATO exercises will run in Swidwin, Poland from May 5 to 9 and will include about 50 soldiers from the 3rd Canadian Division based in Edmonton, comprised of a platoon from 3rd Battalion, Princess Patricia's Canadian Light Infantry and support staff. They were set to leave Friday, Harper's office said in a news release.
"They will conduct training in parachuting, airborne operations and infantry skills alongside Polish and American counterparts in this United States-led exercise with a view to enhancing Alliance interoperability and readiness," the prime minister's office said in the statement.
Canada has also diverted frigate HMCS Regina, which is currently on counter-terrorism and anti-piracy patrols in the Arabian Sea, to help NATO's efforts to send a message of resolve to Russia.
Harper did not say where the ship is headed, but NATO announced earlier this month it was beefing up maritime patrols in both the Baltic Sea and the Mediterranean.
Six Canadian CF-18 fighter jets left their base in Bagotville, Que., this week, headed for an air base in Romania, and eventual patrols along that country's border with Ukraine — and possibly over the Black Sea.
The government also said this week that a Canadian military officer is heading an international arms-control verification team investigating "unusual military activity" in Ukraine, but the inspections won't include the disputed Crimea region, which was annexed by Russia.
National Defence has also announced that a team of navy clearance divers would deploy next month for an exercise in Latvia, one of the Baltic states under threat.