TOKYO -- Japan is preparing to order another 100 F-35 stealth fighter jets from the U.S. to replace some of its aging F-15s, according to sources.

The plan can be considered a response to China's military buildup, as well as a nod to U.S. President Donald Trump's call for Tokyo to buy more American defense equipment. Japan already intended to procure 42 of the new fighters.

A single F-35 costs more than 10 billion yen ($88.1 million), meaning the additional order would exceed 1 trillion yen.

Japan's government plans to approve the purchase when it adopts new National Defense Program Guidelines at a cabinet meeting in mid-December. It will also include the F-35 order in its medium-term defense program, which covers fiscal 2019 to fiscal 2023. The government wants to obtain 42 F-35s as successors to its F-4s by fiscal 2024.

The 42 fighters Japan originally planned to buy are all F-35As, a conventional takeoff and landing variant. The additional 100 planes would include both the F-35A and F-35B, which is capable of short takeoffs and vertical landings.

At present, Japan deploys about 200 F-15s, roughly half of which cannot be upgraded. The Defense Ministry wants to replace the planes that cannot be upgraded with the 100 F-35s, while enhancing and retaining the remaining F-15s.

To accommodate the F-35Bs, the government intends to revamp the Maritime Self-Defense Force's JS Izumo helicopter carrier to host the fighters.

Japan's neighbors are busy introducing their own advanced military aircraft. China deployed its homegrown J-20 stealth fighter in February, and by 2030 some experts expect the country to build a fleet of more than 250 fifth-generation jets -- as the latest generation of fighters like the F-35 is known.

Russia, too, is expected to introduce its fifth-generation Sukhoi Su-57 in 2019, at the earliest.

To keep up, Tokyo believes it is imperative to significantly increase its procurement of the most sophisticated stealth jets.

At the same time, Trump has repeatedly urged Japan to purchase more American hardware and reduce the trade imbalance between the countries. Buying more of the high-priced fighters is a quick way to do that.

In September, Japanese Prime Minister Shinzo Abe told Trump, "Introducing high-performance equipment, including American [materiel], is important for our country to strengthen its defense capabilities."