Trump was praising Putin for the invasion of Crimea at that time......
Within weeks, Trump praised Putin for how he handled the takeover of Crimea and predicted that “the rest of Ukraine will fall … fairly quickly.” Echoing Kremlin propaganda, Trump said in a TV interview that the Crimean people “would rather be with Russia,” a position he also pushed in private. One of his 2016 campaign aides falsely claimed that “Russia did not seize Crimea.”
https://edition.cnn.com/2022/03/26/politics/trump-putin-ukraine/index.html