Former U.S. ambassadors to Middle East countries worry President Trump has encouraged a regional crisis in the Persian Gulf by siding with Saudi Arabia as it leads a coalition to isolate Qatar.

James Jeffrey, a former ambassador to Iraq and Turkey, told the Washington Examiner Trump's vocal favoritism towards Saudia Arabia could upset a Sunni coalition the Trump administration had been trying to fashion to combat Iran and Russia.

"The president is empowering the Saudis, and they will simply take this and blow up what could have been a strong regional coalition against Iran and Russia," said Jeffrey, who served in the Obama and George W. Bush administrations.

In a series of Tuesday morning tweets, Trump took credit for the decision of five Arab nations to suspend diplomatic relations with Qatar, a country that some of its neighbors accuse of supporting Islamist terrorism and Iran.

Trump suggested the decision by the five countries — Saudi Arabia, Egypt, Bahrain United Arab Emirates and Yemen — to cut off Qatar could portend "the beginning of the end to the horror of terrorism!"

But just days earlier, in a May 21 speech before Muslim world leaders in Saudi Arabia, Trump called Qatar a "crucial strategic partner" as he sought to encourage Sunni Arab countries to align together against Iran, the world's largest Shiite nation.

In that speech, Trump said Iran had "fueled the fires of sectarian conflict and terror," signaling a return to American policy built on alliances with Sunni Arab autocrats. Trump was implicitly rejecting former President Barack Obama's approach to the Middle East, which included negotiating a nuclear deal with Iran to the chagrin of Sunni rivals such as Saudi Arabia.

Jeffrey said if Trump's goal is to inspire Sunni Muslim nations to fight terrorism and challenge Iran, which is backing the regime of Syrian President Bashar Assad, he risks upsetting any potential alliance by empowering Saudi Arabia at the expense of its longtime rival, Qatar.

Qatar, a small but energy-rich country, hosts an American airbase — the foreign headquarters of the U.S. Central Command — and is part of the U.S.-led coalition fighting the Islamic State.

Jeffrey noted that like Qatar, Saudi Arabia and other Sunni-led monarchies in the region have also been accused of supporting various Islamist groups in Middle East conflicts. Iran and others, meanwhile, accuse Saudi Arabia of spreading an extreme form of Islam that fuels terrorism.

"This has split the coalition," Jeffrey said. "The idea is you don't let a regional champion become a champion. This has been the U.S. tradition for 70 years. You don't let a regional champion take charge. Trump is taking the side of an ally (Saudi Arabia) that needs to be managed and controlled, not empowered."

Gerald Feierstein, a U.S. ambassador to Yemen in the Obama administration, said members of the Gulf Cooperation Council — a bloc of all Arab states in the Persian Gulf except for Iraq — have long had disagreements about political Islam, and support for extremism. He said U.S. policy traditionally has been to let member countries resolve these complex divisions.

"The U.S. has shared concerns about Qatar in the past, but our position has been these issues are best resolved through dialogue," Feierstein told the Examiner. "The solidarity of the GCC is important to achieve goals in regional security and stability, and while we would like to see changes with Qatar, it is important to do that in a way that does not inflict lasting damage on the GCC."

The move to cut off Qatar, and Trump's support for it, complicates the job of U.S. military leaders and diplomats as it seeks to form a united coalition against ISIS.

Secretary of State Rex Tillerson and Defense Secretary Jim Mattis sought to downplay the dispute in a joint news conference on Monday from Australia.

"I am confident there will be no implications," Mattis said.

Jeffrey says Mattis and Tillerson must reach out to all of the allies in the dispute, and downplay the policy significance of Trump's tweets.

"Basically, as you have to do so often, you ignore the president's tweets and talk to your partners to try and get this thing back to a reasonable place," Jeffrey said.