KALININGRAD, Russia (Reuters) – On the curbside outside the civilian airport in Kaliningrad, Russia’s Baltic Sea outpost, a group of about 20 servicemen in Russian navy uniforms lined up earlier this month, waiting for a bus to take them to their base.

“We are an additional reinforcement,” one of the young men, who said he and his colleagues had flown in that day, told Reuters as they waited on the rain-soaked tarmac. He gave no further details.

Russia and NATO are each building up their military capability across eastern Europe, spurred by the conflict in Ukraine which has prompted officials on both sides to talk of the risk of a new, Cold War-style confrontation.

For Russia, a strategic centerpiece is here in Kaliningrad. A relic of the Soviet Union, it is small piece of Russian territory sandwiched between NATO members Poland and Lithuania, allowing the Kremlin to project its military power into the alliance’s northern flank.

During a three-day visit by Reuters earlier this month, there was ample visible evidence of Russia enhancing its military presence.

Trucks moved military equipment from a port to locations inland, small groups of servicemen flew in, work was under way to boost security near one base and extensive construction was taking place at another base housing a military radar system.

Reuters was able to see only a glimpse of what the Russian military is doing in Kaliningrad. Much of the region is off-limits to foreigners without a special permit and at one point men in civilian clothes ordered photos of military infrastructure deleted. The Russian defense ministry did not respond to questions about its deployments in Kaliningrad.

But much of the activity tallied with what military analysts and Western diplomats say Russia is doing: preparing to station new missiles in Kaliningrad and build a web of anti-aircraft systems that could challenge NATO aircraft over the Baltic states and parts of Poland.