A US soldier is being held in North Korea after crossing the border without authorisation, the US military has confirmed

The soldier was being escorted back to the US for disciplinary reasons before he turned around at the airport and joined a border tour, an official tells CBS News

A witness who was part of the same tour group tells CBS the soldier laughed before running towards North Korea

"I thought it was a bad joke at first, but when he didn't come back, I realised it wasn't a joke," the witness says

US officials tell CBS the man is Private 2nd Class Travis King, who was earlier named in South Korean media

A spokesperson for the US military said they "are working with our Korean People's Army (KPA) counterparts to resolve this incident”

Meanwhile, North Korea has fired a suspected ballistic missile into the Sea of Japan, according to the South Korean military

North Korea has launched a suspected ballistic missile, according to military officials in South Korea.

The missile was fired into the East Sea, also known as the Sea of Japan, Yonhap news agency reported, citing South Korea's Joint Chiefs of Staff. (BBC)