(TOKYO) -- Secretary of State John Kerry arrived in Seoul, South Korea, Friday on a mission aimed at tempering rising tensions on the Korean peninsula.
He urged North Korean leader Kim Jong-un to opt for "the peaceful option being offered."
The start of Kerry's four-day trip to East Asia, which includes stops in China and Japan, came as a wary region braced for another missile launch by Pyongyang.
Kerry met with South Korean President Park Geun-hye in Seoul, reassuring the new leader that the United States would defend its ally, and called North Korea's bellicose rhetoric "simply unacceptable."
In a sign the United States was making efforts to tone down its own rhetoric, Kerry stressed that the two discussed a "bright vision of possibilities" and the prospect of a reunited Korean peninsula "where the aspirations of two Koreas are being made."
"We want to emphasize that the real goal is not reinforcing that we will defend our allies but the possibilities of peace, the possibilities of reunification," Kerry said at a joint press conference with South Korean Foreign Minister Yun Byung-se.
Kerry's visit comes on the heels of an alarming assessment from the Defense Intelligence Agency that expressed "moderate confidence" that North Korea might have a nuclear weapon small enough to be placed on a ballistic missile. The report, made public in a House Armed Services Committee hearing, said the reliability of the missile would be low, but Kerry said it was inaccurate to suggest the Democratic People's Republic of Korea had demonstrated capabilities to "miniaturize" a nuclear warhead.
"Obviously, they have conducted a nuclear test, so they have some kind of device," he said. "Does it get you to a line that is dangerous? Yes."
For the second straight day, President Park stressed the need for talks with North Korea, saying it was time to listen, to end the vicious cycle of provocation. The sudden shift in tone Thursday raised some eyebrows, with sources close to the presidential office saying they were concerned the "olive branch" was made without consulting the United States.
But on Friday, Kerry expressed support for the president's efforts, saying he would not stand in the way of bilateral talks.
"We have agreed, however, to talk very closely about any steps that any of us will take," he said. "It will be a complete and total process before either of us take any steps."
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