From the website of the Defense Department. Edited.

Aegis Ashore in Poland on Target for 2022

The Aegis Ashore capability planned for Poland is moving ahead to be operational by the end of next year, said the program executive officer for Aegis Ballistic Missile Defense.

The Aegis Combat System was originally designed as a shipboard system to track and destroy incoming enemy targets, but now the system has also been deployed for use on land, as “Aegis Ashore.”

Already an Aegis Ashore capability is up and running in Deveselu, Romania, about 90 miles from Bucharest. The site, which is under the control of NATO, has been in operation for more than five years now.

A site similar to the one in Romania is also planned for Redzikowo, Poland, near the Baltic Sea…..[E]fforts are now underway to get the site operational by the end of next year.

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Over the summer, [Rear Admiral Tom] Druggan said, the Aegis system in Poland was pulled out of storage there and assembled to test it’s operations.
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[Druggan] said antennas for the AN/SPY radar system have already been set up.

“We’re installing the backbone of the radar behind it,” he said. “We’ve installed some [command, control, communications, computers and intelligence] systems….”

Druggan said he expects the Aegis Ashore site in Poland to be operational by the end of 2022, and at that point the transition of the system can happen first to the Navy, then to U.S. European Command, and finally to NATO.

SM-3 Block IIA missile of the sort to be ground-based in Poland.