That's quoting pravda.com.ua paraphrasing him, not him directly, and they introduce ambiguity by making it sound a little as if he claimed WW3 is going on for sure and the world's just not realizing it.
In reality he said, "If we don't know whether we're at war, it's always best to assume that we are." At least going by what's in the linked article and the Ukrainian source eurointegration.com.ua it refers to.