U.S. Secretary of State John Kerry has become the first sitting secretary of state to visit the revered memorial to the nuclear bombing of Hiroshima.

Kerry, EU Foreign Policy Chief Federica Mogherini and other foreign ministers from the Group of Seven, who are in Japan for two days of talks, visited the site of the world’s first use of an atomic weapon in warfare on Monday local time.

Their trip was a stark reminder that looming over the current round of G7 talks is the history of the city they’re being held in. It also comes a day after State Department official said Kerry won’t apologize for the twin bombings of Hiroshima and Nagasaki.

Hiroshima was devastated when the U.S. dropped an atomic bomb on the city in August 1945. The bomb, which led to the end of World War II, killed 140,000 people — either initially from the impact or later due to radiation exposure.

Three days later, the U.S. dropped a second bomb on the port city of Nagasaki, killing about 70,000 people.

Under tight security, the diplomats laid wreaths at Peace Memorial Park then walked to the Atomic Bomb Dome. The ruin, which is the only structure left standing near the bomb’s hypocenter, services a as a memorial to the people killed in the bombing.

Beforehand, they toured the peace museum documenting the devastating impact of the attack, which houses victims’ and survivors’ burnt clothing and personal effects.

Together, these three sites stand as a powerful symbol for nuclear disarmament.

‎‎”Everyone in the world should see and feel the power of this memorial. It is a stark, harsh, compelling reminder not only of our obligation to end the threat of nuclear weapons, but to rededicate all our effort to avoid war itself,” Kerry wrote in a message in the site’s guestbook. “War must be the last resort — never the first choice. This memorial compels us all to redouble our efforts to change the world, to find peace and build the future so yearned for by citizens everywhere.”‎

Despite the message’s pacific tone, a senior State Department official traveling with Kerry said emphatically that America’s top diplomat will not issue an apology for its use of nuclear weapons and the devastation it causes.

“If you are asking whether the secretary of state came to Hiroshima to apologize, the answer is no,” the official said. “If you are asking whether the secretary — and I think all Americans and all Japanese — are filled with sorrow at the tragedies that befell so many of our countrymen, the answer is yes.”

Ahead of his visit to the memorial, Kerry spoke with Fumio Kishida, the Japanese foreign minister.

“My visit to Hiroshima has very special meaning about the strength of our relationship and the journey we have travelled together since the difficult time of the war,” Kerry said. “We will revisit the past and honor those who perished, (but) this trip is not about the past; it’s about the present and the future.”

The Japanese government and public hope the location of the summit in Hiroshima will foster better understanding among nations about Japan’s staunch nuclear stance.

Recent comments by Republican presidential front-runner Donald Trump proposing that Japan and South Korea arm themselves with nuclear weapons have raised eyebrows here in the country.

“For us to obtain nuclear weapons is completely inconceivable,” Kishida said.

But Kerry has much more than his visit to the Hiroshima memorial on the agenda.

During the first day of talks, the G7 — which is comprised of the United States, Britain, Canada, France, Germany, Italy and Japan — discussed the Syrian civil war, the migrant crisis facing Europe and violence in Ukraine were some of the topics discussed, aides traveling with Kerry said.

Kerry also led a discussion about the political chaos in Iraq and Afghanistan, after having visited both countries this week. The fight against ISIS also dominated the discussions. Some of the European members are grappling with security challenges in the aftermath of recent terrorist attacks in Brussels and Paris.

But Japan hopes to highlight pressing concerns in Asia, including China’s activities in the South China Sea and the North Korean nuclear threat.

Kerry’s trip to Hiroshima could also pave the way for President Barack Obama to visit the city next month, when he travels to Japan for the G7 leaders summit, fueling speculation of whether he may issue a formal apology for the bombing and the devastation it caused. The senior State Department official said the White House had not made a formal decision.