President Donald Trump holds a proclamation recognizing Israel's sovereignty over the Golan Heights as he is applauded by Israel's Prime Minister Benjamin Netanyahu and others during a ceremony in the Diplomatic Reception Room at the White House, March 25, 2019. Carlos Barria | Reuters

President Donald Trump added a new notch to his belt of shock foreign policy moves Monday night, signing a proclamation officially recognizing Israel's annexation of the Golan Heights, which it captured from Syria in 1967 and has occupied ever since. Trump initially announced the policy about-face last week via Twitter, writing: "After 52 years it is time for the United States to fully recognize Israel's Sovereignty over the Golan Heights, which is of critical strategic and security importance to the State of Israel and Regional Stability!" The decision is major in a few ways. It's yet another rejection by the Trump administration of decades of U.S. policy; it recognizes Israeli sovereignty over a territory internationally recognized as belonging to an Arab state; and it's seen as a boost to Israeli Prime Minister Benjamin Netanyahu ahead of Israel's elections. It also makes things awkward for Washington's Arab allies, whose populations oppose Israeli seizures of Arab lands. Saudi Arabia, Bahrain, Kuwait, Qatar and the United Arab Emirates all rejected Trump's move, calling the Golan occupied Arab territory.

Israeli Merkava tanks participate in a drill near the border with Syria at the Israeli-annexed Golan Heights on May 6, 2013. Uriel Sinai | Getty Images News | Getty Images

In addition, some are calling it a double standard when it comes to the U.S. response to Russia's annexation of Ukraine's Crimean peninsula. "American recognition of the annexation would contravene international law," Ian Bremmer, founder and CEO of risk consultancy Eurasia Group, wrote in an email note this week. "It would be used by the Russians to legitimize their annexation of Crimea," he added. "Plus, it would make movement on the peace plan considerably more awkward."

The US stands alone

The signing, which took place in the White House with Netanyahu present, makes the U.S. the only country in the world besides Israel to recognize the annexed territory, which comprises the western two-thirds of the Golan. Netanyahu called it "historic" while Syria labeled it a "blatant attack on its sovereignty" and pledged to take the territory back by "all available means." Turkey's Erdogan pledged to take action against the U.S. at the UN, while France, Germany and Russia quickly voiced their opposition. Netanyahu also thanked Trump for his controversial relocation of the U.S. embassy from Tel Aviv to Jerusalem last May and for withdrawing from the 2015 Iran nuclear deal.

An Israeli soldier stands next to signs pointing out distances to different cities, on Mount Bental, an observation post in the Israeli-occupied Golan Heights that overlooks the Syrian side of the Quneitra crossing, Israel May 10, 2018. Ronen Zvulun | Reuters

A United Nations spokesman quoted UN Secretary-General Antonio Guterres as being "clear that the status of Golan has not changed" — according to U.N. Security Council Resolution 497 of 1981, Israel's administration of the territory is "null and void." Israel maintains its right to remain there for its own security. The security argument is compelling, analysts say — the U.S. and Israel see Iranian forces using Syria as a launch pad for attacks on Israel, and the Golan is the front line. And Washington's recognition came several hours after a rocket fired from the Gaza Strip hit a residential area just north of Tel Aviv.

What difference does it make?

But despite the international reverberations of Trump's proclamation, this may not make a massive difference to the status quo on the ground, experts say. "In terms of facts on the ground, it doesn't change very much," Graham Griffiths, a senior analyst at Control Risks, told CNBC on Tuesday. "Israel has been occupying this territory for decades now, but this symbolic recognition by the U.S. constitutes a turning point and shows again the extent to which the Trump administration is willing to set aside past U.S. policy precedent to support Prime Minister Netanyahu in Israel."