Israel captured the Golan Heights from Syria during the 1967 Six-Day War and unilaterally annexed it in 1981 via the Golan Heights Law.
However, this annexation is not recognized by the international community. The United Nations (via Security Council Resolutions 242 and 497) considers the Golan Heights to be Syrian territory under Israeli occupation. Most countries maintain embassies in Tel Aviv, not Jerusalem, partly due to this and related disputes.