This article appear to be a bit childish.

The whole issue is that the President of the Ukraine choose to argue in an event that was just ceremonial to an agreement that he agreed to. It was NOT supposed to be a discussion or negotiations. The POTUS and vice president were pissed because the Ukraine president tired to put them in a difficult situation when the media was involved, particularly when he has came in the guise of already having agreed to sign the agreement.

That is literally what the vice president said he said the Ukraine president was being "deeply disrespectful", and know what, I agree.

Not an American by the way.