The New Zealand government on July 9 approved a plan to acquire four Boeing [BA] P-8A Poseidon maritime patrol aircraft for $1.6 billion to replace its six legacy P-3K2 Orion aircraft.

The Poseidons will be bought in a direct source procurement through the U.S. Foreign Military Sales (FMS) program.

The aircraft are scheduled to be delivered in 2023. The New Zealand Ministry of Defense said the current Orion fleet, which has operated since the 1960s, will reach the end of its operational life in 2025.

“The purchase ensures the Defence Force can continue to deliver the country’s maritime surveillance, resource protection, humanitarian and disaster response around New Zealand and across the South Pacific,” Minister of Defence Ron Mark said in a statement.

This is part of the government’s Strategic Defence Policy Statement of 2018, launched in July. It emphasizes the importance of the country’s maritime domain and working with allies and partners and that “maritime security is fundamental to national security.”

The ministry underscored the choice of Poseidons allows the assets to operate either independently or with partners that do or in the future will operate the same aircraft: the U.S., Australia, and the United Kingdom.

The Defence Ministry noted the $1.6 billion cost will be spread over fiscal years through 2025/26. It described this as a “once in a generation purchase,” but it expects the aircraft to be in service for upward of 30 years.

“This is an investment decision that has fallen on this government to make, but will be spread over the medium term and will deliver for New Zealand for many decades to come.”

Starting in July, the government will also start designing the infrastructure needed to house the aircraft at Ohakea Air Force Base. That work is expected to be finished before the Poseidons are delivered. The P-8As will be operated by the No. 5 Squadron, which is moving from Whenuapai to Ohakea.

New Zealand will use the aircraft for protection of the Southern Ocean, participation in international task groups and security operations, search and rescue, humanitarian assistance and disaster relief, and environmental monitoring missions.

The Ministry of Defense said it found Poseidon to have the lowest cost and risk of all available options for these missions.

“Maintaining a maritime patrol capability is essential for New Zealand’s national security, and for our ability to contribute to global security efforts,” Mark said.

The government’s impending Defence Capability Plan, due by the end of 2018, is also considering options for complementary maritime surveillance capabilities, possibly using unmanned or remotely piloted aircraft.

Mark said the ministry is considering smaller manned aircraft, unmanned aircraft systems (UAS), and satellites to supplement the Orions on maritime surveillance within New Zealand’s Exclusive Economic Zone (EEZ) and near-region.

“This will free up the new P-8A fleet to fly more missions, in the South Pacific and further afield,” Mark added.