Armed men waved as they drove in, and some people waved back and shouted: "Well done, lads" and "Russia, Russia."

A show of might by government troops in previously rebel-held Kramatorsk, during which armored personnel carriers flying the Ukrainian flag were driven through the town, were later undermined by a counter-display of force just miles away. In neighboring Slavyansk, several of the same vehicles — this time displaying Russian flags — rolled into the town, stopping outside the rebel-held town hall.

On the eve of talks in Geneva on the plight of the former Soviet country, attempts to recapture state buildings in several towns without bloodshed were faltering.

The Ukrainian government’s attempt to wrest back control of occupied parts of the country’s east was met with defiance Wednesday as pro-Russian armed men appeared to seize army vehicles amid reports of defections to the rebel side.

A soldier guarding one of six troop carriers now apparently under the control of the pro-Russia rebels told Reuters he was a member of Ukraine's 25th paratrooper division from Dnipropetrovsk.

"All the soldiers and the officers are here. We are all boys who won't shoot our own people," he said, adding that his men had had no food for four days until local residents fed them.

A spokesman for the separatists and a witness in Kramatorsk said the Ukrainian troops had given up their vehicles to the rebels after talks.

But Serhiy Sobolev, the head of a parliamentary faction that is part of the governing coalition, asserted that the men who drove the armored vehicles into Slavyansk under Russian flags were in fact Ukrainian soldiers conducting a false-flag operation to move about freely.

"These are our military units who used the partisan method of infiltration into the facilities that today are controlled by Russian military forces and those separatists who are financed by them," Sobolev was quoted as saying by the Interfax news agency.

The uniform worn by some of the men sitting on top of the vehicles was different from that of the gunmen on the ground, many of whom had pro-Russia ribbons attached to their shoulders.

Meanwhile, overhead, a Ukrainian jet fighter carried out several minutes of aerobatics — another apparent show of strength from government forces.

In the industrial city of Donetsk, at least 20 armed rebels occupied the City Council building, a spokeswoman for the council said. The muscle-flexing and inflamed rhetoric heightened fears of violence after Moscow-backed gunmen occupied public buildings in 10 eastern towns and cities in the past week.