U.S. troops will remain in Poland and the Baltic states through 2015 "to deter Russian aggression," the top U.S. commander for Europe said on Sunday.

"There are going to be U.S. army forces here in Lithuania as well as Estonia and Latvia and Poland for as long as it's required to deter Russian aggression," said Lt. General Ben Hodges, commander of U.S. Army Europe.

A former member of the Latvian parliament expressed "surprise" Sunday after Russian media claimed he had been expelled from Russia for spying, in another Cold War-style incident in the ex-Soviet Baltic states.

Aleksejs Holostovs, a former member of the Harmony political party, which draws much of its support from the country's large Russian minority, told the LETA news service he was "surprised" at the allegation of spying from Russia. 

The center-right coalition of Prime Minister Laimdota Straujuma handily won Latvia's elections while a pro-Russian opposition party narrowly won the most seats, near complete official results showed Sunday.

The leftist Harmony party, allied with Russian President Vladimir Putin's United Russia party, took 25 seats in Latvia's 100-member parliament, but with no coalition partners it is set to remain in the opposition, results from 1,000 of 1,054 polling stations showed Sunday.

Latvia's ruling center-right coalition led by Prime Minister Laimdota Straujuma scored a resounding majority in Saturday elections overshadowed by alarm over a resurgent Moscow and a Kremlin-allied party popular with the country's sizable Russian minority.

An exit poll by the SKDS agency gave three parties in her coalition 63 seats in the 100-member parliament, while their Kremlin-allied leftist rival took 23.

Latvia on Thursday said it would open a NATO-backed strategic communications center in the capital Riga amid fears the Kremlin is influencing the Baltic state's large ethnic Russian minority over the Ukraine crisis.

The center will focus on providing an alternative to the official Russian narrative on the crisis and should receive full NATO accreditation "by the end of the summer", the Latvian defense ministry told Agence France Presse.

NATO on Monday launched one of its largest military maneuvers in the Baltic states since tensions spiked with neighboring Russia over its annexation of Ukraine's Crimean peninsula.

Around 4,700 troops and 800 military vehicles from 10 countries including Britain, Canada and the United States are participating in the Saber Strike exercises near the Latvian capital Riga.  

The flag of the self-proclaimed Donetsk People's Republic flew in Riga Friday in a show of support from Latvia's large Russian minority for pro-Moscow separatists in Ukraine.

"It is unfortunate that there are people trying to mar a commemorative event with such provocations," Latvian foreign ministry spokesman Karlis Eihenbaums told Agence France Presse.

Four Danish F-16 warplanes landed in Estonia on Wednesday, marking the first time NATO planes will be stationed in the ex-Soviet state and Russian neighbor. 

The aircraft and a supporting team of 60 people arrived at the Amari air base in the west of the Baltic state at a time when NATO is reinforcing its presence in the region to allay concerns triggered by the Ukraine crisis.

Latvia on Friday welcomed American troops on its soil, part of a U.S. force of 600 sent to the region to reassure the Baltic states amid concern over Russia's actions in Ukraine.

"Today is a special day because this morning I met the heads of the armed forces at the Adazi military base and greeted the U.S. military unit that arrived this morning for military training," Latvian Prime Minister Laimdota Straujuma told reporters.

Latvia has asked the head of the Russian Orthodox church, Patriarch Kirill, to postpone a planned visit amid tension between Russia and the Baltic states over Moscow's actions in Ukraine.

A letter from Latvian President Andris Berzins requesting that the May visit be put off indefinitely was handed to Kirill's representatives in Moscow on Thursday.