‘We’re under no illusions how difficult this is’

President Joe Biden acknowledged Friday there is no easy path to getting North Korea to give up its nuclear weapons but reaffirmed his "iron-clad" commitment to the US alliance with South Korea after talks with President Moon Jae-in. 

"We're under no illusions how difficult this is -- none whatsoever. The past four administrations have not achieved the objective. It's an incredibly difficult objective," Biden told reporters at a press conference with his South Korean counterpart at the White House.

The US leader also announced he had named veteran diplomat Sung Kim, the former US ambassador to Seoul, as his special envoy for North Korea.

Facing a nuclear-armed North Korea and an increasingly assertive China, Biden stressed his faith in traditional US alliances. Biden called the US-South Korean partnership "the linchpin of peace, security" and promised a "shared approach" to the stand-off with North Korea.

Moon called denuclearization of the Korean peninsula "the most urgent common task."

US relations with historic allies in Asia and Europe suffered turbulence under Donald Trump, who recast long-standing partners as cutthroat business competitors and freeloaders.

Moon came to Washington as Biden's second foreign guest and Japanese Prime Minister Yoshihide Suga, who visited last month, was the first.