WASHINGTON — The U.S. Navy, which took over the Aegis Ashore system in Poland after a five-year delay, immediately moved the system into an upgrade and maintenance effort.

The Aegis Ashore system, meant to offer regional missile defense for Europe, has been operational in Deveslu, Romania since 2016, but the Missile Defense Agency struggled to reach operational capability at the second Aegis Ashore site in Redzikowo, Poland, because of construction issues.

Nearly a year ago, then-MDA director Vice Adm. Jon Hill reported those issues were behind MDA, telling reporters the agency was conducting combat system installation and testing. The testing continued through the summer and fall, and the Navy formally accepted the system on Dec. 15, 2023.

The official transfer to NATO is now expected to occur in the spring or summer this year, according to a U.S. Naval Forces Europe/U.S. Sixth Fleet spokesperson.

Now, Aegis Ashore is undergoing maintenance and upgrades. Capt. Raphael Castillejo, the ship integration program manager at the Navy’s Program Executive Office for Command, Control, Communications, Computers and Intelligence (C4I), told Defense News the system is receiving maintenance and modernization efforts similar to those made on Aegis Ashore Romania.

“Typically, these post-delivery modernization availabilities address C4I system upgrades and enhancements for equipment that was procured over five years prior to site completion and address obsolescence, new required capabilities and security enhancements,” he said.

For this Aegis Ashore system, upgrades include the Consolidated Afloat Networks and Enterprise Services network and computing infrastructure system and the Global Positioning Navigation and Timing System.

The maintenance period is expected to take four months, according to the Naval Information Warfare Center Atlantic.

The delays in reaching operational capability have resulted in increased costs. In fiscal year 2021, for example, MDA indicated it would need an extra $96 million in funding to maintain the Aegis weapon system at the site, to keep it protected and in temperature-controlled containers.

The MDA and U.S. Navy declined to say how much the delay has cost the program overall or the cost of the current maintenance and upgrade phase, citing an outstanding congressional inquiry.

Poland’s Aegis Ashore site is part of the European Phased Adaptive Approach to regional missile defense against threats from Iran and includes Aegis radar-capable ships based at Rota, Spain, an AN/TPY-2 radar in Turkey (operational since 2011) and the other Aegis Ashore site in Romania.