Senate Foreign Relations Committee Chairman Bob Corker Robert (Bob) Phillips CorkerHas Congress captured Russia policy? Tennessee primary battle turns nasty for Republicans Cheney clashes with Trump MORE (R-Tenn.) will block arms sales to Persian Gulf states until there’s a “better understanding” of how the Qatar crisis will be resolved, he said Monday.

A Saudi Arabia-led group of countries in the Gulf Cooperation Council (GCC) has cut diplomatic and economic ties with Qatar since earlier this month, citing its relations with Iran and what they say is its support for extremist groups. The situation has pitted United States allies like Saudi Arabia and the United Arab Emirates against Qatar, another U.S. ally that hosts a major U.S. military base.

“All countries in the region need to do more to combat terrorism, but recent disputes among the [Gulf Cooperation Council] countries only serve to hurt efforts to fight [the Islamic State in Iraq and Syria] and counter Iran,” Corker wrote in a letter Monday to Secretary of State Rex Tillerson.

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“For these reasons, before we provide any further clearances during the informal review period on sales of lethal military equipment to the GCC states, we need a better understanding of the path to resolve the current dispute and reunify the GCC.”

Arms sales are subject to preliminary approval by the committee before going to the full Congress for a 30-day review period.

During his trip the Saudi Arabia, President Trump inked a much-touted arms deal with Riyadh worth up to $110 billion that could be thrown into doubt if Corker follows through on his vow.

Last week, the countries delivered Qatar their demands, including shutting news agency Al Jazeera, downgrading diplomatic ties with Iran and closing a Turkish military base.

On Sunday, Tillerson urged the two sides to talk while acknowledging some of the demands will be “very difficult” for Qatar.

“While some of the elements will be very difficult for Qatar to meet, there are significant areas which provide a basis for ongoing dialogue leading to resolution,” Tillerson said in a statement Sunday. “A productive next step would be for each of the countries to sit together and continue this conversation.”

The blockade was imposed shortly after Trump visited the region and delivered a major speech calling on Muslim countries to unite against terrorism and Iran.

Trump has credited that message as the cause for the blockade.

In his letter, Corker said he “could not have been more pleased” with Trump’s trip to Saudi Arabia.

But he contrasted with Trump, saying the GCC did not follow through on promises at the summit to “ease regional conflicts” and “strengthen partnership frameworks,” among other pronouncements.

“We need to remain united in the face of rising threats from Iran and The Islamic State in Iraq and Syria,” he wrote. “Unfortunately, the GCC did not take advantage of the summit and instead chose to devolve into conflict.”

A Corker aide said Monday that the hold applies to all future major arms sales subject to congressional review, which could affect deals "acknowledged or announced publicly by the administration but not formally notified to Congress."

But, aide added, deals that have already been formally noticed to Congress will not be affected, nor will deals for "defensive, non-lethal assistance, including training."

Updated at 4:42 p.m.