Ukraine's President Volodymyr Zelenskyy has declared February 16 as the Day of Unity, a date he says he heard Russia will attack his country.

Zelenskyy made the remark in a video message posted on social media on Monday.

In the message, the president asked his country's people to hoist the national flag and wear ribbons of the same blue and yellow colors on that day to show their unity to the world.

Zelenskyy added that his country aspires for peace and seeks to solve all issues through diplomatic negotiations.

In an apparent warning to Russia, he stressed that Ukraine's military forces have been reinforced since Russia unilaterally annexed Crimea in southern Ukraine eight years ago.