- Donald Trump had claimed the US should encourage Saudi Arabia, Japan and South Korea to develop their own nuclear programs
- Japan's constitution forbids nuclear weapons development and deployment in South Korea would inflame the North's communists
- Obama warned ISIS terrorists could become global menaces if nations don't work harder to keep fissile material out of their hands
- But attention was focused on Trump's from-the-hip pronouncements, with Japan's prime minister and foreign minister slamming him publicly
President Barack Obama warned Friday at a summit in Washington that more cooperation is needed to prevent the ISIS terror army's 'madmen' and other extremists from getting a nuclear weapon.
But the fourth such meeting of Obama's presidency, likely the last before he leaves office, was overshadowed by foreign policy proposals from Republican presidential front-runner Donald Trump.
Trump said this week that allowing Saudi Arabia, South Korea and Japan to develop their own nuclear programs would ease strains on U.S. budgets, given the spiraling costs of maintaining America's nuclear umbrella and foreign troop deployments.
'Japan is better if it protects itself against this maniac of North Korea,' Trump said Tuesday during a town hall event broadcast on CNN.
'We are better off frankly if South Korea is going to start protecting itself ... they have to protect themselves or they have to pay us.'
LET 'EM HAVE NUKES: Donald Trump set the foreign policy world on its ears by saying The U.S. could save money by letting Japan, Saudi Arabia and South Korea have nuclear weapons instead of Americans troops
'MADMEN': President Barack Obama warned that if nations don't band together to shrink the world's supply of fissile material, ISIS terrorists could find it easier to get their hands on it
Peace out! Obama gives the two-fingered peace sign surrounded by an otherwise serious-looking collection of world leaders as they posed for a group summit shot
Those comments followed similar statements in a lengthy interview with The New york Times that set the foreign policy world on fire.
'Would I rather have North Korea have them with Japan sitting there having them also? You may very well be better off if that’s the case,' Trump told the paper.
'If Japan had that nuclear threat, I’m not sure that would be a bad thing for us.'
Aside from Russian president Vladimir Putin's refusal to attend the meeting – it's nearly impossible to achieve reductions in nuclear fissile material without his nation's cooperation – Trump's recent boasts drew the most attention on the meeting's sidelines.
Even Obama's bold words about the threat that terrorists might use nuclear material in a 'dirty bomb' – or even obtaining an atomic weapon – haven't attracted as much attention.
Summit attendees heard, among other things, that ISIS members tracked a Belgian nuclear scientist on video.
'ISIL has already used chemical weapons, including mustard gas, in Syria and Iraq,' Obama said, using his preferred acronym for ISIS.
'There is no doubt that if these madmen ever got their hands on a nuclear bomb or nuclear material, they most certainly would use it to continue to kill as many innocent people as possible.'
PUSHBACK: Japan's Prime Minister Shinzo Abe threw a brushback pitch at Trump after he hinted at a reshuffling of the strategic U.S.-Japan relationship
NO-SHOW VLAD: Russian president Vladimir Putin (left, shown with U.S. Secretary of State John Kerry) didn't come to Friday's nuclear summit in Washington, making efforts to reduce nuclear stockpiles largely moot
But overseas, Trump's unscripted rhetoric has drawn mostly jeers in the countries that might gain their own nuclear defense programs during a Trump administration.
Japanese Prime Minister Shinzo Abe took the unusual step of responding to the billionaire publicly.
'Whoever will become the next president of the United States, the Japan-U.S. alliance is the cornerstone of Japan's diplomacy,' he said.
Foreign Minister Fumio Kishida added that 'it is impossible that Japan will arm itself with nuclear weapons.'
Japan is the only nation to ever suffer a nuclear bomb attack – at the hands of the U.S. during World War II – and its constitution has forbidden the accumulation of nuclear weapons since the war ended.
Daniel Pinkston of Troy University told CNN on Friday that Trump's plan, if executde in South Korea, would play right into North Korea's hands.
'The hardliners in Pyongyang would just love such an outcome because if that were to occur, it would completely justify their nuclear status ... and validate Kim Jong Un's policy line as absolutely brilliant and absolutely correct,' Pinkston said.
'Whether [Trump] wins the Republican nomination or not, or whether he is elected president or not, even at this stage, he is already doing damage to the U.S. reputation internationally. And damaging U.S. security interests.'
Former U.S. Ambassador to South Korea Christopher Hill used fewer words to make a more brutal pronouncement.
'I don't know what he's talking about but clearly neither does he,' he told CNN.
FEAR: North Korea's nuclear program, Trump suggested, would be less powerful if South Korea and Japan had their own nearby
The summit – attended by dozens of world leaders and delegates – is focused on securing global stockpiles of nuclear materials, much of it used in the medical and power industries.
Obama said about 2,000 tons of nuclear materials are stored around the world at civilian and military facilities, some of them not properly secured.
'Just the smallest amount of plutonium – about the size of an apple – would kill and injure hundreds of thousands of innocent people,' he said.
'It would be a humanitarian, political, economic and environmental catastrophe with global ramifications for decades.'
The nuclear security summit comes in the wake of attacks in Paris and Brussels that have killed dozens and exposed Europe's inability to thwart destabilizing attacks or track Islamic State operatives returning from Iraq and Syria.
Evidence that individuals linked to those two atrocities videotaped a senior scientist at a Belgian nuclear facility has given the threat added nuclear weight.
BIG MEETING: Obama and other world leaders gathered in Washington on Friday to air concerns about global nuclear programs
Though the summit is focused on fissile stockpiles, other nuclear concerns inevitably have drawn broad attention, including North Korea and its continued testing of nuclear devices and ballistic missiles.
The reclusive nation fired another short-range missile off its east coast on Friday, the latest in a series of North Korean missile launches during what has been an extended period of military tension on the Korean peninsula.
In January, North Korea detonated a nuclear device -- its fourth such test -- and a month later launched a long-range rocket.
The summit opened Thursday with Obama trying to forge consensus among East Asian leaders on how to respond to Pyongyang.
'We are united in our efforts to deter and defend against North Korean provocations,' Obama said after meeting Japanese Prime Minister Shinzo Abe and South Korean President Park Geun-Hye.
Halfway through the closing day of the summit, delegates described a series of incremental measures, such as enhanced cooperation between nations.
Obama and Abe announced that Japan had removed all its highly-enriched uranium and separated plutonium fuels ahead of schedule. The fissile material will be 'downblended' in the United States for civilian use or eventual disposal.
Obama also used the summit as a chance to speak with his Chinese counterpart Xi Jinping, promising candid talks over Beijing's alleged military buildup in the South China Sea.
US officials have expressed concern that China's actions in the South China Sea are inconsistent with Xi's pledge at the White House last year not to pursue militarization of the hotly contested and strategically vital waterway.
China claims virtually all the South China Sea despite conflicting claims by Brunei, Malaysia, Vietnam, Taiwan and the Philippines, and has built up artificial islands in the area in recent months, including some with airstrips.