US Defense Secretary Lloyd Austin delivers a speech at the Diplomatic Academy, amid Russia's attack on Ukraine, in Kyiv, Ukraine, on Monday. (Reuters)

ROME -- US Defense Secretary Lloyd Austin said on Wednesday there is evidence that North Korean troops are in Russia, and it remained to be seen what they would be doing there.

"There is evidence that there are DPRK troops in Russia," Austin told reporters in Rome, using North Korea's formal name - the Democratic People's Republic of Korea.

"What exactly they are doing? Left to be seen. These are things that we need to sort out," Austin added.

Ukrainian President Volodymyr Zelenskiy has cited intelligence about the preparation of two units with possibly up to 12,000 North Korean troops who would take part in the war alongside Russian forces. (Reuters)