Residents in Hiroshima have greeted President Barack Obama with protests at the site of the world’s first atomic bombing conducted by the US more than 70 years ago.

Obama arrived at Hiroshima's atomic bomb park Friday on the first visit by a sitting US president and was greeted by Japanese Prime Minister Shinzo Abe.

“You’re not welcome here” and “Get out of Hiroshima,” the protesters shouted in a rally held at the Hiroshima Peace Memorial Park.

They held banners that read, “Get rid of all nukes immediately,” “Remove all US bases from Okinawa” and “We won’t let you use military alliances to start your next war.”

Among the protesters, there were labor union members, college students as well as survivors and the relatives of the victims of the Hiroshima bombing on August 6, 1945.

“I could hear schoolchildren screaming ‘Help me! Help me!’ said Kinuyo Ikegami, an 82-year old survivor of the bombing, who took part in the Friday gathering.

"It was too pitiful, too horrible. Even now it fills me with emotion,” she added.

“The suffering such as illness gets carried on over the generation,” said Han Jeong-soon, the daughter of a Korean survivor.

“That is what I want President Obama to know. I want him to understand our sufferings.”

Obama has said he will not apologize for the bombing, which killed thousands instantly, and some 140,000 by that year’s end.

“I want Obama to say ‘I’m sorry.’ If he does, maybe my suffering will ease,” said 73-year-old Eiji Hattori, who was a toddler at the time of the bombing and now has three types of cancer.

“If Obama apologized, I could die and meet my parents in heaven in peace,” he said.

US President Barack Obama and Japanese Prime Minister Sinzo Abe (L) talk before a meeting of Group of Seven (G7) with other leaders at the city of Shima, in Mie Prefecture, May 26, 2016. (Photo by AFP)

Obama's visit to Hiroshima has stirred heated debate, with critics pointing to paradoxes in policies relying on nuclear deterrence while calling for an end to atomic arms.

The city of Nagasaki was hit by a second nuclear bomb on Aug. 9, 1945, and Japan surrendered six days later.

The US justifies the bombings, contending that they were necessary to end the war and save lives, although many historians question that view and believe they were unjustified.

Aides say Obama's main objective in Hiroshima is to showcase his nuclear disarmament agenda. However, critics say he has made scant progress and is spending heavily to modernize the US atomic arsenal.

Japan, despite advocating disarmament, relies on the US nuclear umbrella for extended deterrence.

Among the governments critical of the visit, North Korea on Friday denounced Obama’s visit to Hiroshima as an act of stunning hypocrisy and "a childish political calculation."

“Even if Obama visits the damaged city, he cannot hide his identity as a nuclear war fanatic and nuclear weapons proliferator,” read part of a report on North Korea’s official Korean Central News Agency (KCNA).

Barack Obama paid tribute to the 140,000 people killed by the world's first atomic bomb attack and sought to bring global attention to his unfulfilled vision of a world without nuclear weapons, as he became the first sitting U.S. president to visit Hiroshima.

"Death fell from the sky and the world was changed," Obama said, after laying a wreath, closing his eyes and briefly bowing his head before an arched monument in Hiroshima's Peace Memorial Park that honors those killed on Aug. 6, 1945, when U.S. forces dropped the bomb that ushered in the nuclear age. The bombing, Obama said, "demonstrated that mankind possessed the means to destroy itself."

Obama did not apologize, instead offering, in a carefully choreographed display, a simple reflection on the horrors of war and his hope the horror of Hiroshima could spark a "moral awakening." As he and Japanese Prime Minister Shinzo Abe stood near an iconic bombed-out domed building, Obama acknowledged the devastating toll of war and urged the world to do better.

A second atomic bomb, dropped on Nagasaki three days later Hiroshima, killed 70,000 more."We stand here in the middle of this city and force ourselves to imagine the moment the bomb fell ... we listen to a silent cry." Obama said.

Obama also sought to look forward to the day when there was less danger of nuclear war. He received a Nobel Peace Prize early on his presidency for his anti-nuclear agenda but has since seen uneven progress.

"We must have the courage to escape the logic of fear and pursue a world without them," Obama said of nuclear weapons.

The visit presents a diplomatic tightrope for a U.S. president trying to make history without ripping open old wounds. He did not apologize for the attack, which is viewed by many in the U.S. as having hastened the end of World War II; others have called it a war crime that targeted civilians.

Critics believe Obama's mere presence in Hiroshima will be viewed as an apology for what they see as a justified attack. But he has also drawn praise from those who see it as a long overdue gesture needed to heal old wounds.

Obama touched down in Hiroshima after completing talks with world leaders at an international summit in Shima, Japan.

Those who come to ground zero at Hiroshima speak of its emotional impact, of the searing imagery of the exposed steel beams on the iconic A-bomb dome. The skeletal remains of the exhibition hall have become an international symbol of peace and a place for prayer.

The president was accompanied on his visit by Abe - a demonstration of the friendship that exists between the only nation ever to use an atomic bomb and the only nation ever to have suffered from one. U.S. Ambassador to Japan, Caroline Kennedy, also joined the president.

Bomb survivor Kinuyo Ikegami, 82, paid her own respects at the cenotaph on Friday morning, well before Obama arrived, lighting incense and chanting a prayer.

Tears ran down her face as she described the immediate aftermath of the bomb.

"I could hear schoolchildren screaming: 'Help me! Help me!'" she said. "It was too pitiful, too horrible. Even now it fills me with emotion."

Han Jeong-soon, the 58-year-old daughter of a Korean survivor, was also at the park Friday.

"The suffering, such as illness, gets carried on over the generations - that is what I want President Obama to know," she said. "I want him to understand our sufferings."

Obama's visit is a moment 71 years in the making. Other American presidents considered coming, but the politics were still too sensitive, the emotions too raw. Jimmy Carter visited as a former president in 1984.

Even now, when polls find 70 percent of the Japanese support Obama's decision to come to Hiroshima, Obama's visit is fraught.

His choreographed visit will be parsed by people with many agendas.

There are political foes at home who are ready to seize on any hint of an unwelcome expression of regret.

There are Koreans who want to hear the president acknowledge the estimated 20,000-40,000 of their citizens who were among the dead in Hiroshima and Nagasaki.

There are blast survivors who want Obama to listen to their stories, to see their scars - physical and otherwise.

There are activists looking for a pledge of new, concrete steps to rid the world of nuclear weapons.

There are American former POWs who want the president to fault Japan for starting the war in the Pacific.

US President Barack Obama has called for a world without nuclear weapons during a historic visit to Hiroshima, Japan, where the United States dropped the first atomic bomb nearly 71 years ago.

Obama on Friday visited the site of the world’s first nuclear bombing and met with Japanese Prime Minister Shinzo Abe.

“Death fell from the sky and the world was changed,” Obama said during a speech at the Hiroshima Peace Memorial Park, a site built in the memory of the people who lost their lives in the bombing on August 6, 1945 during World War II.

The US president failed to apologize to the Japanese people for the bombing that killed about 140,000 people. The American atrocity was followed by another atomic bombing on the port city of Nagasaki, killing about 70,000 people on August 9.

Instead Obama told the Japanese audience, which included survivors of the attack, that the horror of America’s nuclear warfare should encourage countries to reconsider the use of the weapons.

“That is a future we can choose,” Obama said, with the Japanese premier standing at his side. “A future in which Hiroshima and Nagasaki are known not as the dawn of atomic warfare but as the start of our own moral awakening.”

“We may not eliminate mankind’s capacity to do evil,” Obama added. “But among those nations like my own that hold nuclear stockpiles, we must have the courage to escape the logic of fear and pursue a world without them.”

US President Barack Obama hugs Shigeaki Mori, an atomic bomb survivor and a creator of the memorial for American WWII POWs killed in Hiroshima, during a ceremony at Hiroshima Peace Memorial Park in Hiroshima, western, Japan, May 27, 2016. (AP photo)

A huge expanse of ruins is seen after the explosion of an atomic bomb in Hiroshima, Japan, on August 6, 1945. (AP file photo)

This is while the United States and its main rival, Russia, reportedly still have some 2,000 atomic weapons ready to fly at a moment’s notice to destroy each other.

And this state of alert is now causing new concerns that the lack of trust between Washington and Moscow has significantly increased the risk of a miscalculation that could lead to a nuclear disaster.

A former commander of US nuclear forces has called on the United States and Russia to take their missiles off high alert to avoid a nuclear disaster.

Retired four-star General James Cartwright said in an interview published by POLITICO in April 2015 that “de-alerting” nuclear arsenals could reduce the risk of firing nuclear weapons in response to a false warning of an attack.

In an interview with Euronews last year, leading American political analyst and philosopher Noam Chomsky said the world is racing toward a nuclear “precipice” and the United States poses the “greatest threat” in this regard.

He said that US President Barack Obama had “initiated a trillion dollar program of modernization of the US nuclear weapon system, which means expanding the nuclear weapon system.”

US President Barack Obama is not a trustworthy leader and his declaration of peace actually means an escalation of war against America’s opponents, an American writer and retired professor says.

James Petras, a professor emeritus of sociology at Binghamton University in Binghamton, New York, made the remarks in a phone interview with Press T on Friday, after Obama called for a world without nuclear weapons during a historic visit to Hiroshima, Japan, where the United States dropped the first atomic bomb nearly 71 years ago.

Obama failed to apologize to the Japanese people for the bombing that killed about 140,000 people on August 6, 1945 during World War II. The American atrocity was followed by another atomic bombing on the port city of Nagasaki, killing about 70,000 people on August 9.

Instead Obama told the Japanese audience, which included survivors of the attack, on Friday that the horror of America’s nuclear attack should encourage countries to reconsider the use of the weapons.

“That is a future we can choose,” Obama said, with Japanese Prime Minister Shinzo Abe standing at his side. “A future in which Hiroshima and Nagasaki are known not as the dawn of atomic warfare but as the start of our own moral awakening.”

“This is another example of the blatant hypocrisy of the Obama administration,” Professor Petras said, “because at the same time he has announced almost one trillion dollars in upgrading nuclear weapons.”

“So in fact the US is moving ahead in escalating the nuclear armament in the United States,” the academic said.

“Secondly, Obama has stationed missiles right on the border with Russia. Thirdly, Obama has stationed US-nuclear armed weapons approximate to China,” he added.

“So on a world scale Obama is moving in an opposite direction, escalating the amount of nuclear weapons available to the US by one trillion dollars, is confronting nuclear weapons against Russia and China,” the analyst said.

“We’ll leave aside the fact that the United States’ government has bombed many countries in the Middle East, Libya, Iraq, and other countries in the region, including Yemen,” he stated.

“So we can see that Obama is totally untrustworthy, that his declaration of peace really means an escalation of war,” Professor Petras concluded.