South Korea, US to Share Nuclear Planning to Deter North Korean Threat

Even so, increasing Seoul's involvement in nuclear deliberations should allow Yoon to argue to his domestic audience that Washington is taking Seoul's concerns seriously.

Duyeon Kim, an analyst with the Center for a New American Security, called the Washington Declaration "a big win for the alliance and especially for South Korea."

She said one of the most notable developments was that the two sides were gaming out scenarios including a U.S. nuclear response, whereas in the past this had been considered too classified to share.

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