The United States, Japan, and South Korea on Sunday vowed a "strong and resolute response" if North Korea carried out a nuclear test.

US President Joe Biden held talks on the matter with allies Japan and South Korea in Phnom Penh on Sunday, on the eve of a meeting with Chinese counterpart Xi Jinping.

Biden, Japanese Prime Minister Fumio Kishida, and South Korean President Yoon Suk-yeol issued a joint statement condemning DPRK's recent barrage, which included an intercontinental ballistic missile.

"They reaffirm that a DPRK nuclear test would be met with a strong and resolute response from the international community," the statement read.

The trio met on the sidelines of an East Asian summit in the Cambodian capital.

"President Biden reiterated that the US commitment to defend Japan and the ROK is ironclad and backed by the full range of capabilities, including nuclear," the statement added, using an abbreviation for South Korea's official name.

Pyongyang ramped up missile launches in response to large-scale US-South Korean air exercises, which it described as "aggressive and provocative."

The tests included an intercontinental ballistic missile and another shorter-range projectile that crossed the de facto maritime border and landed near South Korean territorial waters for the first time since a ceasefire ended hostilities in the Korean War in 1953.

Seoul and Washington have been warning for months that Pyongyang is ready to conduct another nuclear test at any time.

Sunday's joint statement stressed that "the path to dialogue remains open," urging the DPRK to return to negotiations.

The statement, dubbed the "Phnom Penh Declaration," included a pledge to work to boost deterrence.

"The Leaders intend to share DPRK missile warning data in real time to improve each country's ability to detect and assess the threat posed by incoming missiles," it said.

It is noteworthy that last week, the US and South Korea concluded their six-day war games named the Vigilant Storm -- the widest-scale military exercise of its kind, including 240 warplanes conducting 1,600 sorties.

In response, the DPRK said it has responded to the war games by hitting key enemy targets in an exercise.

Pyongyang's military considered that the war games were an "open provocation aimed at intentionally escalating the tension" and "a dangerous war drill of very high aggressive nature," the North's Korean Central News Agency (KCNA) reported.

As a result, the DPRK tested a number of missiles, including an intercontinental ballistic missile (ICBM) and hundreds of artillery shells, in addition to practicing hitting a major South Korean city to "smash the enemies' persistent war hysteria."

In early November, the DPRK issued a warning to the United States and South Korea against continuing their joint military drills, vowing a more powerful response to US provocations. 

"The situation in the Korean Peninsula and its vicinity has entered the serious confrontation phase of power for power again due to the ceaseless and reckless military moves of the US and South Korea," DPRK's Foreign Ministry had said in a statement.

"If the US continuously persists in the grave military provocations, the DPRK will take into account more powerful follow-up measures," Pyongyang warned.

Xi meeting

When Biden meets with Xi on the sidelines of the G20 summit on the Indonesian island of Bali on Monday, he is expected to warn Xi that further North Korean missile and nuclear build-up would mean the United States boosting its military presence in the region -- something Beijing bitterly opposes.

"North Korea represents a threat not just to the United States, not just to (South Korea) and Japan but to peace and stability across the entire region," US National Security Advisor Jake Sullivan told reporters.