The U.S. government says North Korea has yet to respond on the whereabouts of the U.S. soldier who crossed the inter-Korean border into the country while visiting the Joint Security Area on Tuesday.

White House Press Secretary Karine Jean-Pierre said in a briefing on Wednesday that the Defense Department revealed the identity of the soldier as Private Second Class Travis King and reached his next of kin.

She said the White House, the Pentagon and the UN are working together to acquire more information, with attempts ongoing to determine King's whereabouts and safety.

Jean-Pierre said Washington will actively strive to ensure that he is safe and to enable him to come home, adding that the process includes maintaining contact with the Swedish and South Korean governments as well as with the North’s military.

At the State Department, spokesperson Matthew Miller also noted that the Pentagon reached out to counterparts in the Korean People's Army but understands that there has yet to be a response.