SEOUL (Reuters) - South Korean fighter jets flew a patrol on Tuesday over islands disputed with Japan, South Korean President Moon Jae-in said at an event marking the founding of his country’s military, drawing an angry Japanese protest.

A South Korean fighter pilot (L) stands next to his F-35 stealth fighter during a ceremony to mark the 71st Armed Forces Day at the Air Force Base in Daegu, South Korea, October 1, 2019. Jeon Heon-kyun/Pool via REUTERS

South Korea showcased newly acquired F-35 stealth fighter jets to mark its Armed Forces Day as Moon tried to allay concerns that his policy of engagement with neighboring North Korea would weaken South Korea’s commitment to defense.

He said F-15K jets patrolled over disputed islets called Dokdo in Korea and Takeshima in Japan, which are controlled by Seoul but claimed by both, risking inflaming strained ties between the neighbors.

“Just a moment ago, the F-15K, the most powerful fighter-bomber in Northeast Asia, has returned from completing a patrol mission over our land Dokdo ... without any problems,” Moon told the military in a speech.

South Korea’s defense ministry said two of the four jets participating in a patrol flew over the islands.

Japan strongly protested against the flight, one of its foreign ministry officials said on condition of anonymity.

The Japanese official said the islands belonged to Japan historically and under international law and the patrol was unacceptable and deplorable, adding that Japan had asked South Korea not to conduct the flights.

South Korea’s defense ministry said Japan had summoned a South Korean military officer to make its “unfair claims” over the islets.

In the United States, which has been dismayed by the worsening rift between its two key allies in Asia, a spokeswoman for the U.S. State Department said Washington did not take a position regarding the sovereignty of islets, but added:

“Given the recent disagreements between (South Korea) and Japan, the timing, messaging, and increased scale of military drills ... are not productive toward resolving ongoing issues.

“We encourage (South Korea) and Japan to have committed, sincere discussions on resolving these disputes,” the official added.

On Friday, South Korean officials had protested over Japan’s annual defense review that referred to Japan owning the islands. The foreign ministry summoned a military official at the Japanese embassy in Seoul to demand an immediate retraction.

The neighbors have been locked in a worsening diplomatic and trade row rooted in wartime history and disagreements over compensation for forced laborers during Japan’s 1910-1945 occupation of Korea.

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After Japan tightened curbs on exports of high-tech materials vital to South Korea’s chip and display industries in July, each has stripped the other of fast-track trade status.

In addition, South Korea decided in August to terminate an intelligence-sharing pact with its neighbor.

South Korea’s foreign ministry spokesman Kim In-chul told a news briefing on Tuesday that South Korea would only consider renewing the pact when Japan’s “unfair export control measures are resolved”.

In July, a Russian military aircraft twice violated airspace over the disputed islands and drew hundreds of warning shots from South Korean jets, South Korean officials said, during what Russia said was a long-range joint air patrol with China.

Japan, which said it also scrambled fighter aircraft at the time, lodged a complaint with both South Korea and Russia over the incident.

The islands had 28 South Korean residents as of Tuesday, according to South Korean police.

F-35 DELIVERIES

Moon marked Armed Forces Day at a base in the city of Daegu where four of eight Lockheed Martin LMT.N F-35A jets delivered this year were displayed. Forty of the aircraft are to be delivered by 2021.

He made no direction mention of Japan or North Korea in his address, but said the security climate was highly unpredictable, requiring strength as well as innovation.

North Korea has criticized South Korea’s weapons procurements and its joint military drills with the U.S. military as preparations for war that are forcing it to develop new short-range missiles.

Moon has thrown his support behind talks to end North Korea’s nuclear and ballistic missile programs, urging it to talk to the United States.

North Korea’s state news agency KCNA said on Tuesday North Korea and the United States had agreed to resume stalled working-level talks on Oct. 5.