Israel on June 5, 1967 initiated a war against Egypt, Jordan and Syria, describing it as a "preemptive" strike against an impending attack by Egypt which US intelligence determined was in fact non-existing at the time.
On June 6 UN Security Council unanimously adopted resolution 233 (1967) calling for a ceasefire. Egypt and Jordan agreed to a ceasefire on June 8, and at 3 am on June 9 Syria announced its acceptance of the ceasefire. Despite this announcement, Israeli commander Dayan, taking no account of the UN ceasefire resolution, gave the order to go into action against Syria. On the next day, 10 June, Israeli units stopped after completing the final offensive in the Golan Heights. Israel signed the ceasefire the day after, on June11.
In a related maneuver, on June 8 Israel also attacked USS Liberty which was parked nearby in international waters. This attack killed 34 American servicemen and wounded 174.
This delay by Israel in accepting the UN brokered ceasefire underlines the importance of the Golan Heights to Israel.
Israel expelled 130,000 Syrians from the Golan Heights in 1967 and then, in violation of international law, annexed it on December 14, 1980 and immediately moved Jewish settlers and businesses there. There are more than 30 Jewish settlements on the heights, with an estimated 20,000 settlers.
In December1981, a Security Council resolution called the annexation null and void, "without international legal effect".
Ignoring all this, on March 21of this year, Trump tweeted that it was time for the United States to fully recognize Israel's Sovereignty over the Golan Heights. He mentioned "critical strategic and security importance" of Golan Heights to Israel. On Monday, March 25, he signed a decree to that effect.
What is overlooked is that acquiring by force any territory, even one that is of strategic and security importance, is unlawful under international law.
Also, not mentioned is the fact that the area is a key source of water for an arid region. Rainwater from the Golan's catchment feeds into the Jordan River. The area provides a third of Israel's water supply. Golan Heights is the source of River Jordan.
Trump's recognition of Israel's sovereignty over Golan Heights is meaningless. It obviously has only two purposes: 1 to help Israeli PM Netanyahu who, under cloud of being indicted for criminal offenses, is fighting a tough election battle to be re-elected prime minister, and 2 to strengthen his own base, supporters of Israel, particularly American Jews and Christian Evangelicals, in preparation for his own bid to get reelected in 2020