U.S. President Barack Obama is welcomed by South Korean President Park Geun-hye at the Blue House in Seoul, South Korea, Friday. Pic: AP.

SEOUL, South Korea (AP) — President Barack Obama says he is visiting South Korea at “a time of great sorrow.”

The president expressed America’s condolences for the 300 dead or missing after last week’s ferry disaster.

Obama spoke in a press conference Friday with South Korean President Park Geun-hye (goon-hay) at the Blue House, the equivalent of America’s White House.

Park has been consumed by the April 16 maritime disaster, with most of the victims from a high school near Seoul. Obama says with daughters close in age to the victims, he can only imagine their parents “incredible heartache.”

Most of the ferry’s 29-member crew survived. Eleven of them, including the captain, have been arrested on suspicion of negligence or abandoning people in need as the ferry sank. Park recently likened their behavior to murder.

Obama added that the United States and South Korea stand “shoulder to shoulder” in refusing to accept North Korea’s nuclear program.He said the U.S. and South Korea are united in the steps that must be taken. He said North Korea’s threats will get result in nothing but further isolation.Obama was speaking at a joint news conference with South Korean President Park Geun-hye. He says the U.S. and South Korea will deepen their military alliance including missile defense systems.

Obama says the U.S. supports the Korean people’s desire for North and South Korea to be unified. He says the U.S. and South Korea are also working to promote accountability for what he’s describing as serious human rights violations by the North.