Estonia's pro-NATO Prime Minister Taavi Roivas on Wednesday completed formation of a ruling coalition after a March re-election overshadowed by tensions with neighboring Russia.

Roivas's center-right Reform party renewed its partnership with leftist Social Democrats and roped-in the conservative IRL party to command 59 seats in the 101-member parliament, the Baltic New Service (BNS) reported Wednesday.

Estonia's governing pro-NATO Reform party was set Monday for tricky coalition talks after defeating a Kremlin-oriented rival in an election held amid jitters over the actions of neighboring Russia.

President Toomas Hendrik Ilves is expected to task Reform leader and outgoing Prime Minister Taavi Roivas with forming a government after the centrist party won 30 seats in the 101-member parliament in Sunday's vote.

Estonia's ruling Reform Party has emerged as the overall winner in the Baltic country's general election dominated by economic issues and security concerns over Russia's actions in Ukraine.

With all votes counted, Prime Minister Taavi Roivas declared victory early Monday. Polls had predicted a close race between the governing center-right coalition and the opposition Center Party, favored by ethnic Russians.

Estonia's security-minded center-left governing coalition took the lead in Sunday elections, held amid concerns over a militarily resurgent Russia, while the pro-Kremlin opposition lost ground, partial official results showed.

The ruling coalition was leading in 51 of the 101 parliamentary seats with over half of the votes counted.

Estonians voted Sunday in an election marked by jitters over a militarily resurgent Russia and a popular pro-Kremlin party, with the security conscious center-left coalition tipped for a return to power.

Moscow's annexation of Crimea last year and its meddling in eastern Ukraine have galvanized the European Union, including this eurozone member of 1.3 million people, a quarter of whom are ethnic Russian.

Up to 2,000 Russian soldiers took part in drills in the country's west on Wednesday as Moscow conducted an inspection of its paratrooper units in the latest show of strength likely to alarm its neighbors.

Some 500 units of equipment were also to be included in drills in the western Pskov region which borders EU members Estonia and Latvia, defense ministry spokeswoman Irina Kruglova told AFP.

Russia could inflict the tactics it is accused of using to destabilize Ukraine on Baltic members of NATO, Britain's defense minister warned in comments to British newspapers on Wednesday.

Michael Fallon said that NATO must be prepared for Russian aggression in any form, and warned of a "real and present danger" to Baltic members of NATO -- eurozone members Estonia, Latvia and Lithuania.

Estonia's defense minister said a Russian plane had violated its airspace over the weekend, as all three Baltic states and Poland expressed concern over unprecedented Russian military activity in the region.

Russia's actions in Ukraine, including its March annexation of the Crimean peninsula, have spooked neighboring Poland and Baltic trio Estonia, Latvia and Lithuania -- all new NATO members formerly dominated by Moscow.

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 female teacher was shot dead on Monday by a teenage male pupil in a high school rampage in Estonia, the first case of its kind in the Baltic state.

The 15-year-old assailant, who has been taken into custody, used a gun registered to his father, police said.