The U.S. Navy awarded Northrop Grumman Corp. two aircraft contracts worth $350 million over four years, announcing the deals on Sept. 27.

The first contract modification is worth $255 million. The Navy will buy three MQ-4C Triton aircraft, an unmanned high-altitude aircraft used for intelligence, surveillance and reconnaissance. Northrop Grumman (NYSE: NOC) will also supply the Navy with one main operation control station, one forward operation control station, training courseware and unspecified tooling under the deal. Some 30 percent of the work will be done in San Diego. Northrop run the Triton program from its Rancho Bernardo offices and builds the aircraft in Palmdale.

The Triton is very similar to the Global Hawk, which Northrop builds for the U.S. Air Force.

Under the second deal, worth $95 million, the Navy will buy unidentified spare parts, described only as interim spares in support of the Triton’s initial deployment. The majority of work will be done in Baltimore with 11 percent of work in San Diego.

Both transactions are fixed-price deals, with work expected to be complete by August 2020. The Navy said it plans to deploy the Triton aircraft in fiscal 2018, which actually begins in October 2017.

On Sept. 22, the Navy said that the Triton aircraft passed a critical review, known in Pentagon circles as Milestone C. By passing that point, the aircraft program leaves the engineering phase and enters low-rate initial production. The Navy has talked of ordering 68 Tritons. The test flight program to pass Milestone C began in November.

The Naval Air Systems Command of Patuxent River, Md. awarded the deals, drawing on fiscal 2016 aircraft procurement funds.