President Obama arrives in Seoul

SEOUL, April 25 (UPI) -- U.S. President Barack Obama arrived in Seoul on Friday for bilateral meetings with South Korean President Park Geun-hye.

Commenting on the status of relations between the U.S. and Korea, the White House said "our Alliance today is the linchpin of peace and security in the Asia-Pacific region and an increasingly comprehensive global partnership."

Obama took a moment before his meeting with the South Korean president to honor the lost and missing who were aboard the ferry Sewol that sank off the coast of South Korea on April 16. Park accepted the expression of sympathy, telling Obama, "The Korean people draw great strength and courage from your kindness."

While South Korea is in a state of mourning, it is also dealing with on-going tensions with its northern neighbor.

On Thursday, a South Korean official said that North Korea had progressed in its nuclear test preparations. The North has reportedly sealed an entrance to its Punggye-ri nuclear test site, commencing an 11-day countdown in which to undertake the nuclear test or cancel it.

Park and Obama agreed Friday that they would "spare no efforts" to deter North Korea from its nuclear ambitions. Obama's visit to Seoul, Park said, "sends a strong message to North Korea that its provocative acts cannot be tolerated."

Obama also laid a wreath at the National War Memorial to honor those who died during the Korean War.