Spelling and meaning of Russian chant “Ulla”? [closed]

I've encountered some discourse here and there about what Putin and the Russian soldiers chant (typically following a speech). However, when I tried to find accurate information online about what they are saying, how it's spelled or what it means, I can't find anything.

As for its meaning, my hunch is that it is the Russian version of: Hoorah - a common chant among US armed forces. I could be totally wrong though.

Question

What is the accurate spelling of this "ulla"-sounding chant I'm looking for and is it's meaning that of my hunch?