President Yoon Suk Yeol speaks during a Memorial Day ceremony at Seoul National Cemetery on Tuesday. (Yonhap)

President Yoon Suk Yeol praised a recent deal between South Korea and the US that allows for a joint nuclear response to North Korea’s potential nuclear attacks, at an annual Memorial Day ceremony Tuesday, as he called the change an upgrade to the 70-year-old alliance.

The Washington Declaration, announced at a White House summit in April between Yoon and President Joe Biden, dramatically reinforces a US pledge to deliver on deterring North Korea amid its growing nuclear threats, according to Yoon.

“We will use the ever-closer Seoul-Washington ties to maintain watertight readiness to protect the lives and safety of our people,” Yoon said during a speech at Seoul National Cemetery, which is reserved for war veterans, independence movement fighters and several former presidents

North Korea, Yoon stressed, is still advancing its nuclear and weapons program, having written into law how the isolated country would use such weapons as it continues to defy international sanctions prompted by its nuclear buildup. Pyongyang wants sanctions relief before returning to stalled disarmament talks.

Yoon’s remarks are the latest highlight of an administration that since taking power in May last year has been stepping up efforts to hew closer to the US -- Seoul’s biggest ally that is leading a three-way coalition with Japan on denuclearizing the North.

For a stronger united front, Yoon and his Japanese counterpart recently agreed to put behind their differences prompted by Japan’s 1910-45 colonial rule of the Korean Peninsula. Their back-to-back summits that began in March have revived regular visits to each other’s countries by the two leaders after a 12-year hiatus.

At the Shangri-La Dialogue in Singapore on Sunday, an annual summit on security, the South Korean and Japanese defense chiefs settled disputes involving military encounters five years ago, making room for closer security cooperation.

A 2018 incident in which Tokyo said Seoul used its destroyer to lock its targeting radar on a Japanese surveillance plane, a claim South Korea had disputed, had hampered expanding military ties. But the two neighbors would resume working-level talks to start moving past the hurdle, according to Defense Minister Lee Jong-sup, who has stressed joint work on disarming North Korea.

Last week, Pyongyang launched what it claims was a military reconnaissance satellite, amid speculation that the launch could be a cover for missile tests. UN Security Council resolutions ban the North from using such ballistic missile technology.

But the North, which has hinted at a second launch following the failed attempt, instead lashed out at the International Maritime Organization, the UN agency responsible for ship safety. Following the failed test, the group adopted a resolution condemning it, citing its threat to international shipping.

At the Memorial Day ceremony, Yoon underscored pushing back against totalitarian regimes, saying South Korea, a liberal democracy, is built on sacrifices of freedom fighters. Efforts will be underway to retrieve remains of those still missing from the 1950-53 Korean War, Yoon said.

In a show of commitment, the Korean leader and the first lady took part in a burial ceremony of Private First Class Kim Bong-hak, whose remains were identified in February. Pfc. Kim was buried alongside his younger brother, who also died in the war. It was the first time in 12 years for a Korean president to take part in a such a ceremony, Yoon’s office said.