(Reuters) – South Korea’s domestically developed fighter jet successfully completed its first test flight on Tuesday, a defence agency said, amid a push to replace ageing military jets in the face of nuclear and missile threats from neighbouring North Korea.

The next-generation aircraft developed by Korea Aerospace Industries (KAI) in a project partially backed by Indonesia is designed to be a cheaper, less stealthy alternative to the U.S.-built F-35, on which South Korea relies.

A prototype of the jet, dubbed KF-21, took off at 3:40 p.m. from an air force base in the southeastern city of Sacheon, and flew for about 30 minutes, the Defence Acquisition Program Administration said in a statement.

The new jet faces more testing until 2026, when mass production is set to begin.

South Korea unveiled the first prototype of the KF-21 in April last year, hailing the aircraft as the future backbone of its air force and a step towards greater military independence for the U.S. ally in North Asia.

In 2014, South Korea and Indonesia agreed to jointly develop the jet in a project worth 8.1 trillion won ($6.16 billion), with Jakarta agreeing to pay a fifth of the cost.

But in 2018 Indonesia sought to renegotiate the deal, to ease pressure on its foreign exchange reserves, and later offered to pay its share in the form of a barter.

The two countries agreed in November that Jakarta would keep its pledge to shoulder 20% of the development cost, including in-kind payments for a third of its share, though they have yet to formally revise the contract, an official said.

SOURCE REUTERS