The White House announced Wednesday Obama will visit Japan, Malaysia, the Philippines and South Korea in April.
"President Obama is very excited about being able to come and visit, because it's ... a very, very important time," Kerry said Thursday at a news conference in Seoul with South Korean President Park Geun-hye. "There's a lot happening. Frankly, there's too much tension."
Kerry told reporters the United States and South Korea are grappling with "difficult, complicated and historical issues" that required their alliance to remain strong.
"I think North Korea (and) the challenge of their nuclear program remains an essential security issue," Kerry said.
Kerry's meeting with Park will be followed by a trip Friday to Beijing where he will confer with the Chinese government, which remains North Korea's most-important, if not its only, ally in Asia.
A State Department official traveling with Kerry said the trip as "an effort to translate 'de-nuclearization' from a noun to a verb."
The official told the Post Kerry wants to "enlist greater and greater levels of Chinese cooperation in actually helping to achieve the goal of denuclearization, not just talking about it."
Pyongyang, however, ignored Beijing's call for cancellation of last year's test of a nuclear bomb, which led to China showing signs of impatience in government statements and editorials debating China's longstanding support of Pyongyang.
"China's attitude to North Korea is now more dynamic compared to the past when it was always friendly towards Pyongyang whatever it did. It's a substantial change," said Wang Junsheng, a researcher at the Chinese Academy of Social Sciences.