Obama: Trump's comments 'rattle' world leaders

(CNN)President Obama touched on the increasingly rancorous U.S. presidential race at a press conference from the G7 summit in Japan, saying that the presumptive Republican nominee's statements had his fellow leaders concerned.

"Because a lot of the proposals that he's made display either ignorance of world affairs or a cavalier attitude or an interest in getting tweets and headlines instead of actually thinking through what is required to keep America safe," Obama said.

Some of Donald Trump's public statements display "ignorance" or a "cavalier attitude" about the world, he said, without naming the presumptive Republican presidential nominee.

Thursday morning saw the leaders of Japan, the U.S., UK, Italy, Germany, France, Italy and Canada gather in the grounds of the Ise-Jingu shrine, a 2,000 year old temple in Ise-Shima, in Mie Prefecture in central Japan.

Obama is going to Hiroshima Friday to underscore the "very real risks" of nuclear weapons and the "urgency that we all should have," he said.

He is to become the first United States President to visit the Japanese city where the first atomic bomb was dropped.

Obama told reporters at the G7 Summit said that the dropping of the bomb was an "inflection point in modern history" and is something "all of us have had to deal with in one war or another."

He added that the "backdrop of a nuclear event remains something that, I think, presses on the back of our imaginations."

Obama also remarked on importance of reducing nuclear weapons and the progress made in that arena, citing the Iran deal.

Productive meetings

U.S. President Barack Obama told reporters that the meetings so far had been "extremely productive."

"For us to (be able to) get together and focus on critical issues... is vitally important," he said.

He said the meetings had focused on trade and issues facing the global economy, and how the group could work to accelerate growth and "put people back to work," and the importance of stepping back from protectionist policies that leave countries collectively weaker.

European Commission President Jean-Claude Juncker, speaking from Brussels, earlier had reiterated the importance of consensus in moving forward with trade policies which will help bolster the economy.

"We will repeat to our colleagues at the G7 that we believe that solutions should be found at a multilateral level. So we will continue to push for trade agreements which will help boost growth and jobs. We want to shape global trade, through plurilateral, regional and bilateral deals."

Speaking ahead of his visit to Hiroshima, one of two cities that has experienced the horrors of atomic warfare, he said that the "backdrop of a nuclear event remains something that presses on the back of our imaginations."

While a more short-term concern is the role of ISIS and global terror, Obama said that nuclear proliferation, particularly from North Korea, remained a major concern.

"Obviously ISIL using rifles, crude bombs could kill a lot of people in a Paris or a Brussels and people are rightly insisting the world community stamp out ISL and there is a reason why were focused on that," he said, using another acronym for the terror group.

But, he added, "We can't focus on the short term, on the long term when you have a regime that is so isolated and flouts international rules, devotes national resources hell bent on getting nuclear weapons."