WASHINGTON -- The United States maintains ready and capable deterrence against North Korea's evolving threats together with its key allies South Korea and Japan, ranking US officials said Thursday.

They also said the US seeks to institutionalize trilateral defense cooperation between the three countries.

"We share the widespread concern about North Korea's nuclear and missile programs, certainly a concern shared by our allies in the region, notably Japan and the ROK," Siddharth Mohandas, deputy assistant secretary of defense for East Asia, said during a seminar hosted by the Center for Strategic and International Studies, a Washington-based think tank.

"I think what we do in response is to ensure that we, alongside our allies, are maintaining combat credible deterrence," he added, noting that North Korea has fired some 80 ballistic missiles since the start of last year.

ROK stands for the Republic of Korea, South Korea's official name.

Mohandas noted that US deterrence against North Korean threats begins with its conventional capabilities, including some 28,500 US troops stationed in South Korea, and that it is backed by Washington's ironclad commitment to providing extended deterrence to Seoul.

Extended deterrence refers to US commitment to help defense its ally, using all its military capabilities, including nuclear.

President Joe Biden agreed to bolster US commitment to extended deterrence last month when he and South Korean President Yoon Suk Yeol signed a bilateral agreement, dubbed the Washington Declaration, that calls for increased deployment and visibility of US strategic assets to and around the Korean Peninsula.

"We want to make clear, in as strong as possible terms, that our extended deterrence commitment to the ROK is ironclad, is backed by the full range of our capabilities, including conventional capabilities and nuclear capabilities," said Mohandas.

Ely Ratner, assistant secretary of defense for Indo-Pacific Security Affairs, insisted that the Washington Declaration has also reaffirmed South Korea's confidence in US extended deterrence.

The Pentagon officials emphasized the importance of US-South Korea-Japan trilateral cooperation, highlighting the recent thaw in the Seoul-Tokyo relations that they said was possible due to the courage and bravery of the South Korean president and his Japanese counterpart.

"I think the flipside of that is that it is actually in our interest, in all three countries' interest to seek to protect military and defense cooperation from the vicissitudes of politics, and I think the way we do that is by trying to do everything we can to institutionalize trilateral cooperation going forward," Mohandas told the seminar.

Ratner said the US is doing everything it can to institutionalize US network of alliances and partnerships in the region to be "more durable." (Yonhap)