At the Izvaryne border crossing between eastern Ukraine and Russia, it seems to be business as normal. Ukrainain border guards check papers and passports as cars and pedestrians pass through this major crossing.

But these are not normal times. Since the crisis in eastern Ukraine started, the Ukrainian government has introduced much tighter controls on who can cross in to the country. Border officials are on now high alert, and are working at maximum capacity.

Looking for trouble

The signpost at the border shows distances to the main trouble spots in the region: Luhansk, Donetsk and Kharkiv. Border officials want to prevent anyone who they believe might stoke more tensions from entering the country and heading towards the towns where separatists have taken over government buildings.

Guards have put additional screening measures in place to counter an increase in young men crossing in from Russia. Although Ukraine's long border with Russia is difficult to control effectively, they say they have already turned several people back.

"In particular, men aged between 16 and 60 who could not justify the purpose of their trip to Ukraine and do not have sufficient financial means," said Dmytro Lokhtenko, a senior border official at the Izvaryne border crossing.

"The first red flag when they are interviewed is when they are traveling not from the nearby regions, but from further afield," Lokhtenko explained. "We interviewed these people, asked them additional questions. They could not explain the purpose of the trip to Ukraine. And we suspected that they could participate in separatist activities," he concluded.

Ineffective action

The government in Kyiv says Russian men are behind the occupation of local government buildings in eastern Ukraine - such as in the city of Luhansk, around 50 kilometers from the border. It also believes they are stirring up anti-Ukraine and anti-western sentiment.

In Luhansk, pro-Russia demonstrators are already calling for a referendum to join Russia. The Ukrainian authorities have so far appeared powerless to stop the slow takeover of regional government. Ukrainian military action has so far proved ineffective, even though the government has again pledged to act.

No sign of backing down

Yet on the route to the Russian border, police continue to crack down on movements of separatists, setting up several temporary checkpoints. Officers in yellow vests pull over motorists and check for weapons, stopping anyone who appears suspicious.

But these additional controls may not be enough to stop what has already started. The pro-Russia separatist movement seems to be gaining confidence, and shows no sign of backing down.