By Trevor Hunnicutt WASHINGTON (Reuters) – “Yes,” U.S. forces will defend Taiwan if it is invaded by China. Russian President Vladimir Putin is a “butcher” who “cannot remain in power.” And the COVID-19 pandemic is “over.” U.S. President Joe Biden’s tendency to ad-lib in impromptu press situations is often referred to in Washington as his “gaffe” problem. While the term refers to a blunder, Biden’s remarks often aren’t quite that – they betray deeper truths about his thinking and occasionally offer the public a better window into the administration’s approach than that offered by spokespeople,…