The Boeing Company (NYSE:BA) has signed a $2.1 billion deal with the U.S. Navy to build 16 P-8A Poseidon long-range maritime spy planes, the Pentagon announced Tuesday.

The aircraft, which will replace the Navy’s P-3 spy planes after more than 40 years of service, will enhance U.S. anti-submarine, anti-surface warfare and intelligence, reconnaissance and intelligence capabailites. The Navy expects eventually to purchase 117 planes in total, up from the 53 (including the 16 announced Tuesday) it will have once current orders are complete. 

"This milestone is a testament to the incredible effort and dedication of the team to deliver the P-8A to the fleet as planned," Navy P-8A program manager Capt. Scott Dillon said. "The future of the Maritime Patrol and Reconnaissance community has begun to make history with the P-8As already delivered to the fleet. These full-rate production aircraft will give us the opportunity to deliver the best system through a cost-effective procurement contract."

The deal follows on from a $3.6 billion deal that Australia signed for eight P-8A planes, which is based on the fuselage for Boeing’s 737-800 aircraft.

The Poseidon program has cost more than $30 billion since it began in 2009 and will now commence full production following the U.S. order. The U.S. Navy and Boeing hope to make additional sales to the UK, India and New Zealand in the near future, according to a reports by the Times of India and AirForces monthly.