SEOUL/NEW YORK • As North Korea races to build a weapon that for the first time could threaten United States cities, its neighbours are debating whether they need their own nuclear arsenals.
The North's rapidly advancing capabilities have scrambled military calculations across the region, and doubts are growing that the US will be able to keep the atomic genie in the bottle.
For the first time in recent memory, there is a daily argument raging in South Korea and Japan - sometimes in public, more often in private - about the nuclear option, driven by worry that the US might hesitate to defend the countries if doing so might provoke a missile launched from the North at Los Angeles or Washington.
In South Korea, polls show 60 per cent of the population favours building nuclear weapons. And nearly 70 per cent want the US to reintroduce tactical nuclear weapons for battlefield use, which were withdrawn a quarter-century ago.
There is very little public support for nuclear arms in Japan, the only nation ever to suffer a nuclear attack, but many experts believe that could reverse quickly if North and South Korea had arsenals.
Japanese Prime Minister Shinzo Abe has campaigned for a military build-up against the threat from the North, and Japan sits on a stockpile of nuclear material that could power an arsenal of 6,000 weapons. Two weeks ago, Mr Abe won a commanding majority in parliamentary elections, fuelling his hopes of revising the nation's pacifist Constitution.
A MATTER OF POLITICAL WILL
If we decide to stand on our own feet and put our resources together, we can build nuclear weapons in six months. The question is whether the president has the political will.
PROFESSOR SUH KUNE YULL, who studies nuclear engineering at Seoul National University, on South Korea's capability.
US President Donald Trump, who leaves on Friday for a visit to Asia, has intensified these insecurities in the region, engaging in bellicose rhetoric against North Korea and dismissing talks as a "waste of time".
In Seoul and Tokyo, many have already concluded that North Korea will keep its nuclear arsenal, because the cost of stopping it will be too great - and they are weighing their options. Long before North Korea detonated its first nuclear device, several of its neighbours secretly explored going nuclear themselves.
Japan briefly considered building a "defensive" nuclear arsenal in the 1960s despite its pacifist Constitution. South Korea twice pursued the bomb in the 1970s and 1980s, and twice backed down under US pressure.
Today, there is no question that South Korea and Japan have the material and expertise to build a weapon. All that is stopping them is political sentiment and the risk of international sanctions. Both nations signed the Nuclear Non-proliferation Treaty, but it is unclear how severely other countries would punish two of the world's largest economies for violating the agreement.
Seoul has 24 nuclear reactors and a huge stockpile of spent fuel from which it can extract plutonium - enough for more than 4,300 bombs, according to a 2015 paper by Mr Charles Ferguson, president of the Federation of American Scientists.
Japan once pledged never to stockpile more nuclear fuel than it can burn off. But it has never completed the necessary recycling and has 10 tonnes of plutonium stored domestically and an additional 37 tons overseas. "We keep reminding the Japanese of their pledge," said Mr Ernest Moniz, chief executive of the Nuclear Threat Initiative and an energy secretary in the former Obama administration, noting that it would take years if not decades for Japan to consume its fissile material because almost all its nuclear plants have remained offline since the 2011 Fukushima accident.
South Korea may be even further along, with a fleet of advanced missiles that carry conventional warheads. In 2004, the government disclosed that its scientists had dabbled in reprocessing and enriching nuclear material without first informing the International Atomic Energy Agency as required by treaty.
"If we decide to stand on our own feet and put our resources together, we can build nuclear weapons in six months," said Professor Suh Kune Yull, who studies nuclear engineering at Seoul National University. "The question is whether the president has the political will."