The South Korean military has approved a plan to buy 20 maritime patrol aircraft to improve the Navy’s surveillance capabilities of North Korea, a military source said Sunday.

The Joint Chiefs of Staff has recently approved the Navy’s request to add 20 maritime patrol aircraft to supplement the aging squadron of 16 Lockheed Martin P-3C Orions.

“The Defense Acquisition Program Administration is currently working on a plan, which is likely to be an overseas purchase program,” the source said, asking for anonymity as it is not yet open to the public. The budget for the project is estimated at 1 trillion won ($889 million).

Among the potential candidates are Airbus Military’s C-295 MPA, Boeing’s P-8 Poseidon, Lockheed Martin’s SC-130J Sea Hercules, according to officials.

The U.S. Navy has recently received the seventh production of Boeing’s P-8 Poseidon to replace its P-3Cs.

Separately, a naval modernization program has been underway to upgrade P-3C’s radar and censor system by 2016.

Deployed in 1995, the maritime aircraft is capable of conducting various operations in anti-submarine and anti-ship warfare. It is armed with Harpoon Block II air-to-ground missiles and a tactical information system interoperable with the KF-16 fighter jet.

The latest decision comes as Seoul has been putting more resources into coastal warfare and defense capabilities in frontline border islands in the face of North Korea’s growing threat near the tensely guarded western sea.

North Korea has a large fleet of submarines, and one of them is blamed for torpedoing the South Korean warship Cheonan in the Yellow Sea in March 2010, killing 46 sailors. The North also shelled a South Korean border island later that year, killing four people. (Yonhap News)