Flight recorders from the passenger jet that crashed in South Korea last month, killing more than 170 people, stopped working minutes before the plane belly-landed and exploded on the runway, investigators said Saturday.

South Korea's transport minister said on Tuesday he intends to step down to take responsibility for the deadly crash of a Boeing jet operated by Jeju Air on Dec. 29. Jeju Air 7C2216, which departed the Thai capital of Bangkok for Muan in southwestern South Korea,

The flight data and cockpit voice recorders on the Jeju Air jet that crashed on Dec. 29 stopped recording four minutes before the airliner hit a concrete structure at South Korea's Muan airport, the transport ministry said on Saturday.

Ukraine's president said "for those North Korean soldiers who do not wish to return, there may be other options available".

Ukrainian President Volodymyr Zelensky said the wounded North Korean soldiers were taken to Kyiv and are communicating with Ukrainian officials.

The United States warned on Wednesday that North Korea is benefiting from its troops fighting alongside Russia against Ukraine, gaining experience that makes Pyongyang "more capable of waging war against its neighbors.