In separate discussions, Trump spoke with Saudi Arabia’s Crown Prince, Muhammad bin Salman, United Arab Emirates (U.A.E.) Crown Prince, Sheikh Muhammad bin Zayed al-Nahyan, and Qatar’s Emir, Sheikh Tamim bin Hamad al-Thani.

Unity among the Arab partners of the U.S. is essential to promoting regional stability and countering the threat of Iran, Trump reportedly told them.

The leaders “discussed the continued threat Iran poses to regional stability,” the White House spokesperson said. ”The president also emphasized that all countries must follow through on commitments from the Riyadh Summit to defeat terrorism, cut off funding for terrorist groups, and combat extremist ideology.”

On September 7th, Trump said that he’s willing to mediate the dispute between Qatar and other Gulf Arab states, and that he thought a deal could be quickly reached.

Last June, Saudi Arabia, the U.A.E., Egypt, and Bahrain cut diplomatic, trade, air, and shipping ties with Qatar, where the largest U.S. military base in the Persian Gulf is located.

The Saudi-led group of Arab states accused Qatar of having too close of a relationship to Iran, and of being too lenient on Islamic extremists. Doha denies these accusations.

For the first time since the dispute broke out, leaders of Qatar and Saudi Arabia spoke by phone on September 8th, after which Qatar’s Sheikh Tamim bin Hamad Al Thani expressed willingness to negotiate a settlement of their dispute, as reported by media.

Sheikh Tamim and Mohammed bin Salman had “stressed the need to resolve this crisis” through dialogue “to ensure the unity and stability” of the Gulf Cooperation Council (GCC), in their phone discussion, according to reports.

However, shortly after the phone call that hinted at a potential breakthrough in a major diplomatic crisis in the Gulf, there was a dispute over protocol. Apparently, Qatar News Agency’s (QNA) failed to mention that it was Doha that had initiated the call. QNA said that the phone conversation had been coordinated by the US President.

In the meantime, Trump and U.S. Secretary of State Rex Tillerson endorsed an effort to mediate the Gulf Arab dispute by Kuwaiti Emir Sheikh Sabah Al Ahmad Al Sabah, as Kuwaiti officials visited Washington during the week. On September 8th, Tillerson said, “We support his efforts to help bring about a settlement.”

He continued, “The United States and Kuwait both recognize the important of [Gulf Cooperation Council] unity to meet the challenges of the region that we all face together, not the least of which is the threats from Iran.”