F-35 Lightning II pilot US Air Force Captain Kristin BEO Wolfe performs the dedication pass maneuver at the 2020 Fort Lauderdale Air Show in Fort Lauderdale, Florida, the US, on November 21, 2020. (Photo by US Air Force)

The United States has approved the $5 billion sale of advanced F-35 fighter jets to its key regional ally, South Korea.

The US State Department informed Congress on Wednesday that it had approved the sale of 25 of the all-weather stealth multirole combat aircraft made by Lockheed Martin as well as engines and related equipment to the South.

The sale will improve the Republic of Korea’s capability to meet current and future threats by providing credible defense capability to deter aggression in the region and ensure interoperability with US forces, a State Department statement said.

The proposed sale of this equipment and support will not alter the basic military balance in the region, it claimed.

Washington’s major weapons offer to Seoul came after a summit aimed at expressing unity in the face of what both allies called China’s purported growing assertiveness.

The fresh package, which is worth as much as $5.06 billion, requires congressional approval and could take years to complete. Under the arms deal, Seoul would receive top-of-the-line F-35 warplanes along with engines, communications gear and support.

Washington’s peninsular ally has operated Lockheed Martin Corp.’s premier fighter aircraft since 2018.

The US only approves sale of the top warplanes to its closest partners, with Turkey booted from the F-35 program after Ankara purchased the Russian S-400 missile defense systems despite Washington’s repeated warnings.

Washington claims the activation of the S-400s would compromise NATO’s defenses and could give Russia access to intelligence about the American F-35 fighter jets and other military equipment.

The major arms deal between the US and South Korea comes as tensions keep mounting with North Korea, which carried out its latest missile tests just as its leader Kim Jong-un visited Russia to discuss greater cooperation with Russian President Vladimir Putin, who is deeply engaged in a full-scale war with Ukraine since February last year.

The US has boosted three-way cooperation with Japan and South Korea, both home to American troops. Over 28,500 American troops are based in South Korea as a legacy of the 1950-1953 Korean War, which concluded in an armistice rather than a peace treaty.

Back in August, US President Joe Biden, South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida held a meeting at the Camp David presidential resort near Washington, promising to work more closely together on North Korea and other challenges.

North Korea, which has been under harsh sanctions by the United States and the United Nations Security Council for years over its nuclear and ballistic missiles programs, launched an unprecedented number of missiles in 2022, including its most advanced intercontinental ballistic missile ever.

Seoul, which has been rattled by increased North’s test launches, is now trying to boost its military alliance with the US and deepen cooperation with Japan.