Ukrainian President Volodymyr Zelenskyy says there has been “rather unusual activity” along the Ukraine-Belarus border. He has expressed concern about the possible involvement of Belarus in Russian attacks.

Zelenskyy said in a video address on Saturday that such activity was detected on Friday near the border on the Belarusian side.

He did not disclose details, but said Kyiv is closely taking note of everything.

Zelenskyy said Ukraine is ready to defend its people and sovereignty. He said anyone who is being drawn into any aggressive action against Ukraine must understand this.

Last month, Zelenskyy said the construction of roads toward Ukrainian territory and the development of artillery positions were underway in Belarusian border areas, citing intelligence. He said Russia might once again attempt to drag Belarus into its conflict.

Russian forces continue their attacks on Ukraine. The Ukrainian air force says the Russian military used a ballistic missile and more than 260 drones from Saturday night through Sunday, causing deaths and injuries.