Even now the UN already handles the Golan Heights. After the Yom Kippur War, the UN Security Council approved Resolution 350, that created a demilitarized zone in part of the Israeli-occupied territory of the Golan Heights in Syria. It's monitored by the UN Disengagement Observer Force.
Just because Israel and the US have rejected a U.N. peacekeeping force, that doesn't preclude some other monitoring entity.
Examples of other DMZs not formed through the UN, but by treaties, declarations or resolutions.
-- Åland – The Åland Convention of 1921, which was concluded following a decision of the League of Nations in response to the Åland crisis, mandates that the Finnish government maintain the territory as a demilitarized area.
-- Korean Demilitarized Zone – The Korean Armistice Agreement created a 4 km (2.5 mi)-wide demilitarized zone between North Korea and South Korea following the Korean War.[3] It is currently one of the most heavily militarized areas in the world despite the name.
-- Kuwait–Iraq barrier – The United Nations Security Council approved the creation of a demilitarized zone between Iraq and Kuwait in Resolution 689 after the Persian Gulf War. Although the demilitarized zone is no longer mandated by the council, it continues to exist.
-- Sinai Peninsula – The Egypt–Israel peace treaty sets a limit to the amount of forces Egypt can place in the Sinai Peninsula. Parts of the peninsula are demilitarized to various degrees, especially within 20–40 kilometres (12–25 miles) of Israel. Israel also agreed to limit its forces within 3 kilometres (1.9 miles) of the Egyptian border. The areas are monitored by the Multinational Force and Observers. Because of the Sinai insurgency all sides agreed and encouraged Egypt to send large amounts of military forces into the area, including tanks and helicopters, to fight Islamist groups.
DMZs prevent extremist rockets & armed attacks, and lower stress that can lead to a space for further talks.
Analyst Jeremy Bash brought up considerations of part of Gaza being a DMZ at least a couple of weeks ago.
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