Standing alongside South Korean President Park Geun-Hye at the White House, Obama told a press conference that the US alliance with close ally Seoul was "a lynchpin of peace and security" for the Korean peninsula and the region.
"Kim Jong-Un's missile program achieved nothing except to deepen North Korea's isolation," said Obama, referring to the North Korean leader.
"Today, President Park and I are reaffirming our nations will never accept North Korea as a nuclear weapons state."