The Navy’s oldest deployable warship is preparing to return to service after undergoing extensive maintenance and several upgrades.

The 7th Fleet command flagship Blue Ridge has been in dry dock at Yokosuka Naval Base in Japan for 19 months, Stars and Stripes reported.

The Blue Ridge is the Navy’s second oldest active ship. The oldest, the USS Constitution, is primarily ceremonial.

Blue Ridge entered dry dock in June 2016 and was scheduled to remain there for 14 months, a period that was ultimately extended while its communication system was overhauled as part of a plan to extend the ship’s service life into 2039.

The overhaul included the installation of the proprietary Consolidated Afloat Networks and Enterprise Services (CANES) system, which will enhance Blue Ridge’s communication security and adaptability, and will make it the most advanced communications vessel in the fleet.

The Blue Ridge and its sister vessel, the 6th Fleet command flagship Mount Whitney, based in Gaeta, Italy, were designed in the 1960s. They are said to be the most sophisticated communications and intelligence ships ever created and have been integral to naval operations in both hemispheres.

The Blue Ridge is currently moored pierside, but is not ready to resume operations just yet.

Additional upgrades will include modernizing the ship’s engineering and electrical plants, as well as its living quarters. Blue Ridge should resume service in the next several months and, if all goes as planned, remain active for the next 20 years.