Months after initial reports that Russia was upgrading its nuclear weapons storage bunker in its Kaliningrad exclave, there is more news regarding Moscow’s military upgradation in the region.

According to a CNN report, Russia is appearing to upgrade four of its military installations in Kaliningrad. Kaliningrad is Russian territory sandwiched between Poland and the Baltics but disconnected from Russian mainland. It is a strategic Russian outpost on NATO's doorstep.

In July, satellite imagery gathered by Planet Labs and reported by Defense One had shown activity around bunkers in Baltiysk, a town that hosts a major Russian port and two air bases.

Between March and June this year, Russia appeared to have carried out the fortification of buildings, characteristic of explosive storage bunkers.

Now in fresh imagery from the area captured between July and October, analysts have identified new work on an exposed bunker under renovation that appears to conceal activity underneath.

The CNN reports another set of images shows 40 new bunkers under construction, increasing capacity at a military storage area near Primorsk, Russia's second-largest port on the Baltic Sea. There’s also work done on the Chkalovsk air base, including a new railway and the installation of an instrument landing system to allow aircraft to land in bad conditions.

Russian weapons and the upgradation in Kaliningrad have been a point of contention with NATO. In late 2016, Lithuanian President Dalia Grybauskaite said the transfer of nuclear-capable Iskander missiles to the exclave "means an aggressive, open demonstration of power and aggression against not the Baltic states but against European capitals."

Iskander missiles have a range of about 310 miles and in the past were stationed in Kaliningrad on a temporary basis. But in February, Grybauskaite said Russia had deployed more of the missiles there "for permanent presence."

The missiles and facility upgradation in Kaliningrad have raised concern about threats to Western Europe, and the exclave also positions Russian forces near the Suwalki Gap, a weak point in the NATO alliance.

Ever since Russia annexed Crimea from Ukraine, tensions have been high in eastern Europe and the NATO countries.

(The above story first appeared on LatestLY on Oct 18, 2018 08:42 AM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).