Japan will lease five military aircraft to the Philippines that the latter plans to use to patrol territories it claims in the disputed South China Sea.
Japanese Defence Minister Gen Nakatani "reaffirmed the transfer" of the TC-90 surveillance planes in phone talks with his Philippine counterpart Voltaire Gazmin, said the Philippines' Defence Ministry spokesman Arsenio Andolong in a statement.
This is yet another sign of deepening security ties between the World War II foes, in the face of China's growing territorial ambitions.
Under a deal first announced in March by Philippine President Benigno Aquino, Japan will lease up to five TC-90s and help the Philippines train pilots and aircraft mechanics.
Mr Aquino had said the planes would be used to patrol the South China Sea.
Tensions in this vital waterway have risen since China began turning at least seven reefs into islands with military-grade airstrips. Last month, China began operating a 55m lighthouse on one of these islands, near where a United States warship sailed last year to challenge China's territorial claims.
China has also deployed missiles and fighter jets to Woody Island, part of the Paracel island chain in the northern half of the South China Sea, near Vietnam.
A report in the Hong Kong daily South China Morning Post said China plans to start reclamation work on Scarborough Shoal, about 200km west of the Philippines, later this year. Plans include building an airstrip there that will extend the Chinese air force's reach.
US Defence Secretary Ashton Carter told a congressional hearing last week that Scarborough "is a piece of disputed territory that, like other disputes in that region, has the potential to lead to military conflict".
China claims most of the energy- rich waters of the South China Sea. But neighbours Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims.
"We agreed that it is important for all the countries in the region to strengthen cooperation in order to maintain peace and stability of the South China Sea," Mr Nakatani told reporters.
"We believe that improving the Philippines' capability will lead to stability in the region," he added.
It will be Japan's first lease of its Self-Defence Forces' aircraft to another state after it recently lifted a self-imposed ban on arms exports.
With a range of some 1,900km, the TC-90s will double the area that the Philippines can patrol.
The Philippines, saddled with a severely under-equipped military, has been seeking to strengthen ties with Japan as tensions mount over the South China Sea.
In February, Japan agreed to supply it with military hardware, which officials said may include anti-submarine reconnaissance aircraft and radar technology.
Japan has its own dispute with China in the East China Sea over uninhabited islands it administers that are also claimed by Beijing.
The Japanese warship Ise last month sailed into a Philippine port near the South China Sea.
It marked the third time that vessels from the Japan Maritime Self- Defence Force visited the Philippines this year. A minesweeper visited in March and the submarine Oyashio, along with two destroyer escorts, docked on April 3.
The French frigate Guepratte, meanwhile, will arrive in the Philippines today for a "goodwill visit", the Philippine Navy said.