"The Americans have just informed us that on December 15, in a few days time, the operational capability will be reached by the missile defence shield in Redzikowo," Morawiecki said of the facility, stationed 250 kilometres (155 miles) from the Russian exclave of Kaliningrad.

Over 10,000 US troops are currently stationed in Poland, a NATO member on the alliance's eastern flank and one of the staunchest supporters of neighbouring Ukraine.

According to US and NATO officials, the system in Redzikowo was built to counter the threat of short- and medium-range ballistic missiles, particularly from the Middle East.

But the project of a US-built base in Poland was slammed by Russia as a serious security threat.

The Redzikowo base, plans for which were first announced in 2009, was intended to include 24 land-based SM-3 missiles as well as anti-aircraft systems.

A similar US facility -- officially called Aegis Ashore -- is already up and running in Romania.