According to Anders Åslund, a former Atlantic Council senior fellow, Sullivan has advised Zelenskiy not to try to recapture Crimea or to strike the Kerch Bridge that connects the occupied peninsula with Russian territory. Sullivan’s apparent reasoning is that this may spark a nuclear war.
Like an idiot saying: Let's not poke the bear, better to just give them what they want. Also it's Russian rhetoric.
Kyiv, however, does not agree and frequently targets Crimea.
Go Ukraine, giving in to a bully only encourages it.