Sen. Bob Corker (R-Tenn.) is chairman of the Senate Foreign Relations Committee. (J. Scott Applewhite/AP)

The chairman of the Senate Foreign Relations Committee said Monday that he would “withhold consent” from all U.S. arms sales to Persian Gulf countries until the ongoing dispute between Saudi Arabia and Qatar is resolved.

While congratulating President Trump on signing a joint statement of unity last month with the Gulf Cooperation Council, Sen. Bob Corker (R-Tenn.) said in a letter to Secretary of State Rex Tillerson that recent conflicts among GCC members “only serve to hurt efforts to fight ISIS and counter Iran.” ISIS is an acronym for the Islamic State.

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

It was unclear what power Corker has to stop what the administration has said were $110 billion worth of arms deals signed with the Saudis during President Trump’s trip there last month. Laws governing such sales require congressional notification but not formal consent, although administrations for decades have upheld an informal practice of obtaining approval from the two committee chairmen before officially notifying Congress and triggering a 30-day review process.

If an administration chooses to ignore the chairmen, sales can be stopped only by a joint resolution of both chambers.

But regardless of its legal standing, Corker’s statement serves to buttress Tillerson’s efforts to move the GCC parties toward resolution. Many lawmakers have grown increasingly uneasy at the White House’s perceived tilt toward Saudi Arabia, which they see as practicing its own ultraconservative interpretation of Islam, and acting at the expense of other U.S. regional partners.

A Senate resolution to block a $510 million sale of precision-guided munitions, which had been withheld by the Obama administration on the grounds that the Saudis were using U.S. weapons indiscriminately in Yemen, was only narrowly defeated earlier this month.

A Corker aide said that “major lethal arms sales to any GCC member state that have been acknowledged or announced publicly by the administration but not formally notified to Congress could be affected.”

“Until lifted” by Corker, the aide said, “it could impact portions of the deal announced by the Trump administration in Saudi Arabia that have not yet been formally notified to Congress.” The deals include naval vessels, helicopters, tanks and other major weapons systems that Trump has variously said would bring “thousands” and “tens of thousands” of defense industry jobs to the United States.

The regional dispute began early this month when GCC members Saudi Arabia, the United Arab Emirates and Bahrain, along with Egypt, broke relations with fellow GCC member Qatar, imposed restrictions on its land borders and airspace, and expelled its citizens.

The other countries charged Qatar with supporting terrorism and attempting to undermine their governments, and they criticized what they said were Qatar’s too-friendly relations with Iran. Trump immediately expressed support for the move, while Tillerson and Defense Secretary Jim Mattis called for mediation.

Over the past several weeks, Trump has repeatedly sided with the Saudis, calling what is in effect a blockade of Qatar “hard but necessary,” while Tillerson has warned of negative humanitarian and military effects. Qatar is the regional headquarters of the U.S. Central Command and hosts an air base from which U.S. counterterrorism strikes in Syria, Iraq and Afghanistan are planned and launched.

Last week, a State Department spokeswoman said the department was “mystified” over the failure of the blockaders to come up with a promised list of complaints against Qatar and actions they were demanding to resolve the situation.

“At this point, we are left with one simple question: Were the actions really about their concerns about Qatar’s alleged support for terrorism, or were they about the long-simmering grievances between and among the GCC countries?” spokeswoman Heather Nauert said.

The six-member collection of authoritarian monarchies has always been less than cohesive, with the Saudis claiming leadership and Qatar challenging its dominance and differing on issues such as forming a working relationship with Iran, which Qatar favors.

The list of demands on Qatar, which was leaked Thursday, included requirements that Qatar shutter its popular Al Jazeera news channel — which has been critical of neighboring monarchies — and scale back its relations with Iran. Of all the GCC countries, only Saudi Arabia and Bahrain do not have formal diplomatic relations with Iran.

It also demanded that Qatar close a Turkish military base in that country and sever ties with “terrorist organizations,” including the Muslim Brotherhood.

Some of the 13 demands addressed long-standing concerns about Qatar’s support for extremist groups and a more liberal interpretation of Islam. But others, including a requirement that Qatar pay compensation to the Saudis and others for “policies” that have damaged them internally, appeared designed to punish Qatar for its failure to recognize Saudi leadership in the region.

Tillerson said in a statement Sunday that “Qatar has begun its careful review and consideration of requests presented by Bahrain, Egypt, Saudi Arabia and the U.A.E.”

“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.