President Donald Trump on Thursday announced that Morocco and Israel have agreed to normalize relations, making Morocco the fourth Arab nation in four months to recognize Israel. Part of this deal will include the United States recognizing Morocco’s claims over the disputed Western Sahara region, according to reports.

Trump said that the two countries would establish normal diplomatic ties and other relations, which will see the immediate reopening of liaison offices in Tel Aviv and Rabat, followed by the eventual opening of embassies. Additionally, there would be joint overflight rights for airlines, U.S. officials said.

“Another HISTORIC breakthrough today!” he tweeted late Thursday morning. “Our two GREAT friends Israel and the Kingdom of Morocco have agreed to full diplomatic relations – a massive breakthrough for peace in the Middle East!”

A major caveat of this deal will see the U.S. recognize Morocco’s controversial territorial claims over the disputed Western Sahara region, which the kingdom administers partially. Up until this point, top global powers have, for the most part, tried to stay out of the dispute.

The decades-long dispute dates back to the messy Spanish decolonization of northwestern Africa, resulting in violence breaking out in the 1970s over control of the region. Multiple parties still contentiously dispute who controls Western Sahara. The main competitor to Morocco’s claim is the Sahrawi Arab Democratic Republic (SADR), which seeks an independent Western Sahara and is mostly backed by neighboring Algeria and Mauritania. Mauritania, it should be noted, also occupies a southern portion of the region.

This dispute has caused diplomatic troubles for Morocco, complicating its relations with its North and West African neighbors and with the 55-member African Union. The United Nations recognizes neither Morocco’s nor the SADR’s sovereignty over the region.

In two separate tweets on Thursday, Trump firmly emphasized that the U.S. is ready and willing to recognize these disputed claims, citing that Morocco recognized the U.S. as an independent nation in 1777, one year after the U.S. declared its independence from Britain.

“Today, I signed a proclamation recognizing Moroccan sovereignty over the Western Sahara,” Trump posted to Twitter. “Morocco’s serious, credible, and realistic autonomy proposal is the ONLY basis for a just and lasting solution for enduring peace and prosperity!”

“Morocco recognized the United States in 1777,” he wrote in another tweet one minute later. “It is thus fitting we recognize their sovereignty over the Western Sahara.”

In September, the U.S. successfully brokered a peace deal between Israel and the United Arab Emirates and then a separate one with Bahrain, known as the Abraham Accords. In the months since the U.S. spearheaded similar negotiations that have resulted in Sudan agreeing to establish normal relations with the Jewish State. These historic milestones have all largely been seen as a monumental foreign policy victory for Trump.

The first Arab countries to recognize Israel were Egypt in 1979 and Jordan in 1994, both under different circumstances.

You can follow Douglas Braff on Twitter @Douglas_P_Braff.