I would think he means to say that there is a parallel between Germany and Austria & Russia and Ukraine. The Germans 'annexed' (the term in German is Anschluss, which means 'connection' - it's the word used to talk about your internet connection today) Austria in 1938 under the guise of 'protecting German-speaking peoples'. Your uncle is probably trying to draw his own connection between this and the Russian 'annexation' of Ukraine under the guise of 'protecting ethnic Russians'.

It is an admittedly clear similarity, but it is unclear what your uncle believes it is a 'sign' of. Presumably he thinks it is a precursor to some sort of Russian world-takeover scheme, as many people retroactively see the Anschluss? As this is a history subreddit and not a political one, I will refrain from speculating as to the plausibility of that. However, I will add that just because one country decides (even illegally) to annex (or invade) another does not mean that it is attempting to start a world war. Many countries have done this throughout history with no such consequences (including the United States - see, the Mexican-American War and the Spanish-American War).