An E-6B Mercury prepares for takeoff at Naval Air Station Patuxent River, Md., Aug. 8, 2022. (Christopher Hurd/U.S. Navy)

The Navy has taken delivery of an improved version of the aircraft that links the upper echelons of government with U.S. submarines carrying nuclear-tipped missiles, according to Northrop Grumman.

After a year of modifications, the defense contractor returned the E-6B Mercury this week, part of $111 million in planned upgrades to the airborne command post fleet, according to a company news release Tuesday.

Northrop added five kits that make efficiencies and improve the aircraft’s command, control and communications functions, according to the release.

The Mercury, a modified version of Boeing’s 707 airliner, provides a “survivable, reliable and endurable” link between the president, defense secretary and U.S. Strategic Command and the country’s nuclear forces, including Navy ballistic-missile submarines, according to Northrop and a 2021 Navy fact sheet.

“Northrop Grumman is leveraging cutting-edge technology in modernization, supporting the Navy’s mission to provide survivable, reliable and endurable airborne command, control and communications,” Scott Pfeiffer, company vice president for platform sustainment and mission readiness, said in the release.

The work was carried out at the company’s aircraft maintenance and fabrication center in Lake Charles, La., Northrop said.

Work on a second aircraft is already underway, the company said.

Two Mercury squadrons — Fleet Air Reconnaissance Squadrons 3 and 4 — deploy more than 20 aircrews from Tinker Air Force Base, Okla., according to the Navy.

The plane can fly 600 mph and as high as 40,000 feet with a range of 7,590 miles.

Under the contract awarded in February 2022, Northrop over the coming years will establish a consolidated production line and continue modifications to the remaining Navy E-6Bs, the company said.