Ukraine's ambassador to Japan said it is necessary to assume the worst-case scenario regarding Russia's military attack on his country.

Sergiy Korsunsky told reporters in Tokyo on Friday that Russia has fired missiles at civilian facilities, causing many casualties.

He added that attacks will likely continue, and that Russia probably aims to take all of Ukraine's territory -- an outcome he called a "maximum scenario."

Korsunsky stressed that Ukraine has no intention of surrendering, and is ready to fight back.

He also said that it is "absolutely unacceptable that one person created such a crisis for no reason," and added that Russian President Vladimir Putin "must be stopped."

The ambassador called on Japan to strengthen sanctions on Russia in coordination with the international community.