Ukrainian President Volodymyr Zelenskyy said his country has intelligence information suggesting that North Korea is preparing to send ten-thousand troops to join Russian forces in the fight against his country.

Zelenskyy made the remarks Thursday in a press conference after meeting with the European Union leaders in Brussels, Belgium, calling any North Korean involvement “the first step to a world war.”

He said Ukraine will raise the issue if it obtains information about the deployment of the troops.

He also said North Korea has already sent tactical personnel and officers to Ukrainian territory temporarily occupied by Russia, adding he could not give the exact number.