TOKYO/BEIJING Since North Korea sent an intercontinental ballistic missile soaring 3,700km into the sky on July 28, Shinzo Abe and Donald Trump have spoken by phone six times -- sometimes for close to an hour. In each of these conversations between the Japanese prime minister and the U.S. president, Trump has gone to great lengths to offer assurances that the U.S. stood behind Japan "100%." He sometimes repeated the phrase as many as five times in a single call, according to Japanese government sources.
For Abe, who has sought to build strong ties with Trump since his election, the president's words were a welcome change from the rhetoric of his campaign, when he frequently attacked the cost of U.S. defense commitments in Asia. Despite Trump's assurances, however, Japanese political and military leaders have started to question the strength of the security compact that has underpinned the relationship between the U.S. and Japan in the postwar era. Under its pacifist constitution -- which Abe would amend if he could -- Japan relies on the U.S. to carry out offensive military strikes. But a North Korea equipped with nuclear ICBMs might change the equation: Could the Americans still be counted on to fight for Japan if doing so carried the risk of losing Los Angeles or New York?
"When North Korea has been armed with nuclear weapons, the security regime under the current Japan-U.S. alliance, however strong, may be unable to fully protect Japan's safety," said a security-related Japanese government official.
Japan is not the only country in the region questioning decades old policies and alliances as North Korea moves closer to developing nuclear missile capability. Kim Jong Un, North Korea's unpredictable 33-year-old leader, has gone out of his way this year to provoke China's president, Xi Jinping. That has prompted some in Beijing who had previously tolerated the regime's behavior to conclude that he must be reined in. In Seoul, President Moon Jae-in has agreed to allow the deployment of U.S. anti-missile launchers, reversing a key campaign pledge, amid concerns of a split between his administration and Trump's. And in Tokyo, military planners say the country's missile defense system requires an urgent, and costly, upgrade to deal with the new threat.
Some Japanese security experts predict Pyongyang could be able to deploy the weapons within two years or even sooner -- a time frame that is not expected to move much even after the new sanctions passed by the U.N. Security Council on Sept. 11. If North Korea succeeds in developing nuclear missile technology, Asia could witness an arms buildup unlike anything seen since the Cold War, experts say. China has complained loudly about Moon's decision to deploy more of the U.S. anti-missile launchers in South Korea, and any increase in Japan's capacity also would be seen in Beijing as a threat to its security.
"Calls are growing in South Korea for acquiring nuclear weapons in response to the North Korean threat. Japan is also talking about deploying Aegis missiles on its own mainland," said Masao Okonogi, a North Korea expert and professor at Tokyo International University. "No matter how they do it, their military buildup will increase tensions in the region, especially vis-a-vis Russia and China."
Okonogi and others say they do not expect a nuclear "domino effect" in the region, given Japan's firm opposition to the weapons and South Korea's commitments under the non-proliferation treaty. But any friction over military expansions would add new risks in an already tense region, where disputes over territorial claims, fishing rights and China's island-building have sparked periodic conflicts in recent years.
"I don't think the region becomes more stable" in the coming years, said Tetsuo Kotani, senior fellow at the Japan Institute of International Affairs. "There may be more chances for accidents."
HOW MANY MISSILES IS ENOUGH? It has been an anxious summer. Trump's vow on Aug. 8 to deliver "fire and fury like the world has never seen" -- followed by North Korea's promise to consume Guam, home to a U.S. military base, in "enveloping fire" -- raised worries that the two leaders could be on the brink of war. South Koreans, who over the years have become accustomed to erratic and threatening behavior from the North, have grown worried, with 76% saying in a poll last week that North Korea's latest nuclear test threatens to disrupt the peace on the peninsula. And in Japan, the anxiety came to a head at 6 a.m. on Aug. 29, when a ballistic missile flew across the island of Hokkaido before falling into the Pacific Ocean. The launch triggered a J-Alert, the national emergency system, with residents in the northern part of the country receiving a text from the government reading "Missile passing."
Few in Tokyo military circles think North Korea would carry out a pre-emptive strike on Japan with nuclear missiles. The concern is more that a conflict on the Korean Peninsula could escalate to the degree that it triggers a nuclear attack by the North. There is another worry: that Trump could launch military action against North Korea without consulting Japan first. This is one reason Abe tries to speak to the U.S. president as often as possible.
These concerns have crystallized the sense among the country's leadership that Japan's missile defense system isn't up to the job of fending off nuclear threats. They want to significantly upgrade its defensive capabilities, which are made up of a ship-based Aegis system equipped with interceptors designed to shoot down ballistic missiles, and the surface-to-air Patriot Advanced Capability-3, or PAC-3, missiles.
Critics say this is no longer enough. Japan has four Aegis ships, and three of them must be deployed at all times in the Sea of Japan to provide basic protection. But these ships can carry only a limited number of interceptors, making it difficult for Japan to fend off a possible onslaught of North Korean missiles. "The Aegis ships may exhaust all interceptors and be forced to return to ports to reload," according to a former Japanese Defense Ministry official.
If the Aegis interceptors miss any of the oncoming missiles, then it becomes the job of the PAC-3 missiles to shoot them down. But they are mainly deployed in urban areas, and each of them can only protect an area of 10 kilometers in radius. That leaves much of the country unprotected.
To overcome this weakness, Japan plans to introduce the Aegis Ashore land-based interceptor system, which can cover a wider area -- just two units can cover all of Japan -- but deployment is several years away. Another problem is cost. A single interceptor for the Aegis system, for example, is said to cost some 2 billion yen ($18.5 million).
The expense has alarmed some in the Japanese government, but others -- including former Defense Minister Satoshi Morimoto -- say the country needs to spend even more on a new missile defense system.
"Aegis Ashore will be budgeted next fiscal year, but in addition to that, we're going to have to consider onboard laser weapons that can destroy a missile in the ascending phase," Morimoto said.
There is another, more radical, idea being discussed within the Japanese government: giving its Air Self-Defense Force the ability to directly attack North Korea's missile facilities. In other words, allowing Japan to aim missiles at North Korean launchpads, rather than wait until the missile comes its way. This would mark a dramatic change in Japan's defense structure.
Japan has stuck to its exclusively defensive posture based on Article 9 of its postwar constitution. Since 1956, however, the country has maintained the position that the constitution would allow it to attack enemy bases if there is no other way of self-defense. Japan relies on the U.S. military for its attack capability for defense purposes.
Yukio Okamoto, a security expert and former Japanese Foreign Ministry official, believes Japan should seriously consider the idea. "In discussing ways to respond to North Korea's nuclear arms development, Japan should debate the possibility of allowing itself the capability to attack missile-launch bases," Okamoto said. "If Japan gained such a capability, North Korea would be made aware that it risks retaliation by not just the U.S. but also Japan when it launches a military action against Japan."
Others say this is misguided. "The system is very expensive at a time when we're facing financial problems," Kotani said. "I don't think it should be a priority. The priority is missile defense."
In South Korea, Moon has opposed calls from conservatives to create a nuclear arsenal of its own, but he is expanding defense spending. He has announced plans to spend $38 billion on defense next year, compared with $35 billion this year. And South Korean defense minister Song Young-moo recently announced plans for a new "decapitation unit" capable of performing raids across the border.
The military expansions in Japan and South Korea hardly represent a full-scale regional arms race, says Kotani. "We are just responding to North Korea and China. The scale and pace [in Japan and South Korea] is totally different" than the military buildups in those countries, he said. "Perhaps they will use our buildup as an excuse to build up more."
PUSHING CHINA'S BUTTONS Kim Jong Un achieved two of his objectives on Sept. 3: He oversaw the successful test of a hydrogen bomb, and in the process he managed to embarrass Xi Jinping. Eager to project an image of global leadership at a BRICS summit in China, Xi was instead upstaged by Kim for the second time this year. His appearance at a conference in May heralding China's $1 trillion Belt and Road Initiative was also overshadowed by a North Korea missile launch.
For some in China, North Korea's largest trading partner and its economic lifeline, the latest episode was too much. "We are reaching the end of our tolerance. We need to put much stronger pressure on North Korea," said a researcher at a think tank affiliated with the Chinese government.
The researcher had opposed tough sanctions against the North, such as an economy-crippling oil embargo. But the latest nuclear test changed his mind. Others in and around government in Beijing who had valued North Korea as a buffer with the U.S. have come to similar conclusions.
The new sanctions imposed by the U.N. Security Council this week stopped well short of the full oil embargo sought by the U.S., instead cutting crude oil and petroleum products bound for North Korea by 30%. The full embargo was opposed by China and Russia, but the relatively speedy agreement by the council was an indication that both countries agreed some penalty was warranted.
The Chinese are loath to impose sanctions that might result in the collapse of the North Korean regime. One concern about imposing a full oil embargo is that it could result in an economic free fall, causing a swarm of refugees to flock across the border into China. Less likely is that the North could retaliate by training its missiles in China's direction, but even the Chinese find Kim's behavior to be hard to predict.
For China, a full oil embargo would also represent the loss of a diplomatic trump card to use in its dealings with the U.S. Beijing sees an oil embargo as a potential last bargaining chip to stop the U.S. from taking military action against North Korea.
Still, it has become clearer that China has less leverage with North Korea than many in the West had assumed. But it would be a mistake to believe it has none. "China has economic leverage," says Kotani. "If they exercise it, they can still shape North Korea."
As Kim well knows, the missile crisis is coming at a complicated time for Xi, who wants to avoid anything that might blur the optics ahead of the once-every-five-years National Congress of the Communist Party of China, to be held next month. Xi is reluctant to take any actions that risk detracting from the Congress, where he is expected to win a second term.
There are risks to inaction, too. If China gives an impression that the country keeps its arms crossed during a crisis, it could hurt Xi's authority. Messages critical of the Chinese government's lack of action after the North Korean hydrogen bomb test, which caused an earthquake in China, have been rising on the internet. "Although years have passed since the nuclear power station accident in Japan [in 2011], we are still worried about radiation. Why do we remain a silent observer of neighboring North Korea's nuclear test?" said one.
But in this case, at least, the Chinese authorities were able to follow a well-worn script. Wary of the surge of negative comments, China tightened its censorship of the internet. Weibo, the Chinese counterpart of Twitter, has cracked down on any searches including the words "hydrogen bomb."
Nikkei staff writers Mitsuru Obe in Tokyo and Kim Jaewon in Seoul contributed to this report.