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.

Russia will modernize and relaunch a Soviet-era radar station on the Crimean peninsula annexed from Ukraine to provide early warning of missile strikes, a senior defense official said Saturday.

The radar station in the port city of Sevastopol will become fully operational in 2016, the commander of the air and space defense forces, Alexander Golovko, was quoted as saying by the TASS news agency.

Ukrainian President Petro Poroshenko on Friday risked further angering the Kremlin by suggesting that English lessons replace Russian ones in schools to improve the country's standard of living.

"English should become the second language to be taught in schools," Poroshenko said on a visit to Lviv, a nationalist bastion of political support for the new pro-Western leader where Russian speakers make up a minority.

Ukrainian troops and pro-Russian forces were engaged in fresh clashes in the eastern city of Donetsk on Friday as they traded blame over the death of a foreign aid worker four weeks into their shaky truce.

Shelling in the center of the main rebel-held city in Ukraine's east killed a Swiss Red Cross worker Thursday, tearing badly at a weakly observed four-week truce meant to defuse Europe's worst crisis in decades.

The attacks in Donetsk were the first to strike the heart of the city since the signing of the truce on September 5 between Kiev and Moscow.

Pro-Russian insurgents launched a fresh assault Thursday on an airport held by isolated Ukrainian forces as a month-old truce came under renewed strain and calls grew for the Kremlin to help halt the bloody revolt.

Ukraine also dispatched its energy chiefs to Brussels in a bid to convince the European Union to back up Kiev at crunch talks with Russia on the latest energy war with its westward-leaning but effectively bankrupt neighbor.

New NATO chief Jens Stoltenberg said Wednesday Russia must reverse course in Ukraine but stressed the alliance still remains ready to have a constructive relationship with Moscow.

Russia's intervention in Ukraine "is a major challenge to Euro-Atlantic security", former Norway prime minister Stoltenberg told his first press conference as NATO head after replacing Anders Fogh Rasmussen.

The city, on the frontline in the five-month-old conflict between Kiev forces and pro-Russian separatists, has been shattered, with hardly a building still intact.

Houses have burned down and parks are pocked with mortar craters; few cities in the region around the rebel stronghold of Lugansk have been hit as hard as Pervomaisk.

Russia on Wednesday vowed to protect its citizens in the Moldovan region of Transdniestr, warning "those who don't think like us" not to meddle in the pro-Moscow breakaway region.

"There is no need to indulge in any illusions about whether Russia will protect its own citizens," the state news agency TASS quoted Deputy Prime Minister Dmitry Rogozin as saying.

He has been tormented by a bloody pro-Russian uprising and the near-bankruptcy of his young but bitterly conflicted former Soviet state.

Now President Petro Poroshenko's success in handling both crises will be tested when Ukrainians pick a new parliament that could make or break his post-war revival plans.