Since the 1967 Six-Day War, the Arab residents of these territories have lived under a military occupation, with no representation in the Israeli government.
Netanyahu praised President Trump twice during his speech, once for recognizing Jerusalem as Israel's capital and again for recognizing the Golan Heights as Israeli territory. He said recognizing Israel's sovereignty over the Golan Heights was a "good and important start."
Some see Trump recognizing the Golan Heights as a part of Israel as a precursor to him recognizing the rest of the territories occupied by Israel since the Six-Day War. Netanyahu does know how to play to Trump's ego, recently promising to name a settlement in the Golan Heights after him.
Netanyahu could be in trouble since he failed to form a new government after being reelected in April, Israeli Parliament voted to dissolve and Israelis will be heading back to the polls on September 17th. Back in April Netanyahu made a similar pledge in the run up to the elections, saying he would begin annexing the occupied West Bank if reelected.