I think the poster you're replying to is just regurgitating the common right-wing talking point that Obama was a war-monger, and that Trump did not start any new wars. (Counterpoint: Under Trump, air strikes rules of engagement got loosened, and more civilians died: https://watson.brown.edu/costsofwar/files/cow/imce/papers/20... ).

On the topic of foreign policy fuck-ups, another consequence of Trump is that countries about to do deals with the USA under Biden will ask, "So, will this deal be undone in when the next administration comes to power?" and will be more hesistant or they'll manage to get a better bargain because of the US's loss of reputation.