(CNN) Japan is preparing an order for roughly 100 US-designed F-35 stealth fighter jets in a deal that could potentially upend the balance of power in Asia, according to sources familiar with the process.

That order would include a version of the jet that can take-off and land vertically, a feature that could prompt Japan to transform some of its existing ships into aircraft carriers so that it can operate the fighters at sea -- a capability they have not had since World War II, a source close to the F-35 program told CNN.

"With short take-off vertical landing capability you are now able to operate at sea. You are able to penetrate areas and reach ranges in a shorter distance which is an important capability," the source said.

Japan's Defense Ministry would not confirm the deal, but said it would be looking to buy a "highly competent fighter jet" when its "midterm defense maintenance plan" comes up for approval by Prime Minister Shinzo Abe's cabinet in December.

The ministry said almost half of its existing F-15J fighter jet fleet cannot be upgraded, making the purchase of new planes necessary. "At this point, the concrete model has not been decided," the ministry's press office said.

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But a source close to the US F-35 program confirmed to CNN that a deal was being worked on for Japan to buy about 100 of the stealthy single-engine F-35s.

The Pentagon touts the F-35, with the world's most advanced avionics, engines and weaponry, as the "the most affordable, lethal, supportable and survivable aircraft ever to be used."

Some 40 of the order would be F-35Bs, capable of short take offs and vertical landings on a warship, confirmed the source.

Adding credence to the report, Japanese Defense Minister Takeshi Iwaya said Wednesday that Tokyo is seriously considering refitting at least one of its Izumo helicopter destroyers to accommodate jets, essentially transforming one or both of the 27,000-ton vessels into aircraft carriers.

"Since this is valuable equipment that we already own, I think it would be desirable to use it for as many purposes as possible," Iwaya said in a news conference held after a Cabinet meeting.

Nikkei News Service put the value of the fighter jet deal at $8.8 billion, with the value of each jet at $88 million.

The move, which critics allege violates the country's postwar pacifist constitution, comes amid Chinese naval expansion in the Pacific Ocean. A Japanese defense white paper in August highlighted concerns over Asia's changing security environment.

"China's rapid modernization of the People's Liberation Army, enhancement of operational capabilities, and unilateral escalation of activities in areas close to Japan are generating strong security concerns in the region and international community, including Japan," the paper said.

F-35 fighter aircraft from the Japan Air Self-Defense Force take part in a military review at the Ground Self-Defence Force's Asaka training ground in Asaka, Saitama prefecture on October 14, 2018.

Speaking to CNN, Timothy Heath, senior defense analyst for the RAND Corp, said that China's ambition to dominate the Asia-Pacific region carries "enormous consequences for Japan."

"It is in Japan's interest to build a capable military that deters China from rash actions and to help other countries balance politically and military against Chinese power," said Heath.

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At the same time, the Trump administration's unconventional approach toward trade and military alliances has left Tokyo feeling, at times, unsure of the extent of US support in recent months which had underpinned its international relations since the end of World War II.

President Donald Trump has repeatedly urged military allies in east Asia to pay for their own defense, teasing the end of a US military presence in the region while encouraging Japan to buy more American weapons.

The F-35, in particular, has been a favorite of Trump, who has publicly touted international sales of the aircraft as a success for his administration and praised foreign leaders who have purchased the fifth-generation aircraft.

Japan's commitment to purchase additional F-35's is, in part, an effort to reaffirm its military partnership with the US, according to the source close to the program, who noted that the aircraft not only provides an upgrade in capability but also facilitates strength in allied partnerships.

"The President has put a big emphasis when he travels the globe on military partnerships, industrial partnerships and Japan is certainly a strong partner for the US military. When you see great focus on the F-35 from Japan I think that is the result of the very strong US-Japan military partnership," the source told CNN.

'Push the front line of maritime engagement'

Sources said the new Japanese-US deal would include two of the three F-35 variants, the A and B models. The third, the F-35C, is designed for use on the US Navy's largest aircraft carriers.

F-35As, of which Japan already has 10 in its fleet, with 32 more on an preexisting order, are conventional jets, using a runway to take off and land.

F-35Bs are short take-off and vertical landing capable, meaning they can use smaller airports or operate from flattop warships. The US Marine Corps flies F-35Bs off US Navy amphibious assault ships, sometimes called baby aircraft carriers as they are about half the size of the US Navy's Nimitz-class carriers.

Japan's Maritime Self Defense Force possesses two of these type of ships, the Izumo and its sister ship, the Kaga, each one is capable of carrying 14 helicopters and would need to be refitted to accommodate the F-35Bs aircraft.

The Japan Maritime Self-Defense Force ship JS Izumo sails the South China Sea with the US guided-missile destroyer USS Dewey.

While the main role of Japan's military remains defense of its home islands, "this could push the front line of maritime engagement further out than before," said Corey Wallace, Asia security analyst at Freie University in Berlin, said of Japan's possible acquisition of F-35Bs.

"Will it bother China? Probably, but only in so far that it further complicates the projection of Chinese military power into the southwestern maritime domain around Japan's Ryukyu islands," Wallace said.

An article published in the Chinese state-run Global Times newspaper, Wednesday, said the refit of the Izumo-class ships, and the purchase of the F-35Bs, "essentially changes the warships' nature from a defensive to offensive one."

The story continued: "Japan must not forget its infamous history of invading countries and regions in the Asia-Pacific region during WWII."

China's own answer to the F-35, the domestically built twin-engine J-20 stealth jet, entered the People's Liberation Army Air Force fleet in February. It is unknown how many J-20's China has in operation in its fleet at present.

Carl Schuster, a former US Navy captain and now Hawaii Pacific University professor, said the F-35Bs on a Japanese warship "add a new dimension" and "a deterrent factor" to the security situation in the Pacific.

But Schuster said a refitted Japanese carrier would likely only carry six to eight F-35Bs, compared to as many as two dozen jets that will be on Chinese carriers now in sea trials or production.

Schuster also cautions that it could be three or four years until newly ordered F-35s reach the Japanese fleet, unless Tokyo's orders are given priority over other buyers of the plane.

The Japanese Air Self-Defense Force maintainers pose for a photo during the arrival of the first Japanese F-35A at Luke Air Force Base, Arizona.

Strength in numbers

Twelve nations besides Japan and the US are in the F-35 program, with two of those -- Australia and South Korea -- in the Pacific region, according to Lockheed Martin, which builds the plane.

Japan does enjoy the advantage of being one of three final assembly points for the F-35, the others being in Texas and Italy.

And it's the F-35 commonality between Japan, the US and their allies that brings strength in numbers but also understanding.

Wallace said the future could conceivably have US F-35s operating from Japanese ships and or Japanese F-35s flying off American ones.

One of the other two nations to operate the F-35B, the United Kingdom, has had US versions of the jet operating off its HMS Queen Elizabeth aircraft carrier.

But Wallace also warned not to overemphasize the importance of a Japanese carrier.

"This singular new carrier won't carry enough planes, or be able to launch jets with enough ordnance to conduct strike, or bombing missions in any way that will truly threaten China's mainland, given how strong China's own defenses are," he said.

What F-35Bs will do is increase the options available to Japanese defense planners.

"The F-35B can operate from modified runways or make-shift airfields thereby giving Japan's Air Self-Defense Force (ASDF) more options to operate from smaller, more distant Japanese islands in a pinch. This is quite important for survivability and response if the major airbases are put out of commission in a saturation missile attack," he said.