President Obama arrived in Seoul, South Korea, Friday to news that North Korea may be counting down to a nuclear weapons test.
Such moves out of Pyongyang are no surprise and are typical for the North's behavior, Obama told reporters while in Tokyo, his previous stop on his Asia trip.
The President said he is prepared to deliver a firm response, if a test is conducted during his visit.
North Korea's heightened activity at its nuclear test site was already known. But now the final step needed for an underground detonation has been taken, a South Korean government official said Thursday.
The North has closed off the entrance to the tunnel at the Punggye-ri nuclear test site, the official said.
That gives Pyongyang 11 days to either detonate a nuclear device or cancel the test. It would be the North's fourth test of a nuclear weapon.
We're expecting a live news conference from the President within the hour. We'll bring it to you when it starts on "Early Start."
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Seoul, South Korea (CNN) - The South Korean president on Monday warned North Korea that any provocative moves will be met with "a strong response" as the United States deployed stealth fighter jets in the tense region as part of joint military exercises.
"If there is any provocation against South Korea and its people, there should be a strong response in initial combat without any political considerations," President Park Geun-hye said at a meeting with senior defense and security officials, according to her office.
Her comments came after North Korea rattled off fresh volleys of bombastic rhetoric over the weekend, declaring that it had entered a "state of war" with the South and labeling the U.S. mainland a "boiled pumpkin," vulnerable to attack.
On "Early Start" this morning, CNN's Kyung Lah reports on South Korea's response to North Korea's increasingly hostile rhetoric.