Saudi Arabia and its allies have reportedly threatened to retaliate against the United States over a law that allows the families of 9/11 victims to sue the Gulf Arab kingdom in U.S. court for any role it may have played in the 2001 attacks.

White House and top Pentagon officials have warned the contentious bill would place American troops and interests at risk.

The Associated Press (AP) explains:

The kingdom maintains an arsenal of tools to retaliate with, including curtailing official contacts, pulling billions of dollars from the US economy, and persuading its close allies in the Gulf Cooperation Council [GCC] to scale back counterterrorism cooperation, investments and US access to important regional air bases.

Earlier this week, Defense Secretary Ash Carter sent a letter to Congress saying “important counterterrorism efforts abroad” could be harmed.

He indicated that enacting the bill into law “could be devastating to the U.S. military” and warned that it “could lead to the public disclosure of American secrets and even undercut counterterrorism efforts by sowing mistrust among U.S. partners and allies,” reports AP.

Chas Freeman, former U.S. assistant secretary of defense for international security affairs and ambassador to Saudi Arabia during operation Desert Storm, told AP the Saudis could retaliate in ways that place America’s strategic interests at risk, like permissive rules for overflight between Europe and Asia and the Qatari air base from which U.S. military operations in Afghanistan, Iraq, and Syria are directed and supported.

“The souring of relations and curtailing of official contacts that this legislation would inevitably produce could also jeopardize Saudi cooperation against anti-American terrorism,” he said, according to AP.

Despite all the warnings, the legislation became law despite President Barack Obama’s veto. Both Senators and Congressmen voted Wednesday in favor of overriding the president’s move. The vote passed the bill as a statute, marking the first time Congress has quashed a veto during Obama’s two terms in office.

The GCC, a six-member coalition of Gulf Arab states that includes Saudi Arabia, expressed concern when the U.S. Congress passed the bill earlier this month. Saudi Arabia, a longstanding ally of the United States, has been described as the GCC’s most powerful member.

In a statement issued September 12, Abdullatif al-Zayani, secretary general of the GCC, said the law “contravenes the foundations and principles of relations between states, notably sovereign immunity,” adding that it “will create a grave precedent.”

“This should be clear to America and to the rest of the world: When one GCC state is targeted unfairly, the others stand around it,” Abdulkhaleq Abdullah, an Emirati Gulf specialist and professor of political science at United Arab Emirates University, told AP after the U.S. senate’s veto override Wednesday.

“All the states will stand by Saudi Arabia in every way possible,” he also said.

Abdullah noted that if the bill is enacted into law, he expects the GCC will take action that is more assertive and independent of the U.S. in places like Yemen, Bahrain and Egypt.

“This is not just a threat. This is a reality,” he declared.

Of the 19 al Qaeda plane hijackers who carried out the September 11, 2001 attacks that killed nearly 3,000 people on U.S. soil, 15 called Saudi Arabia home.

In an op-ed that was first published on the London-based Saudi daily Al-Sharq Al–Awsat, Abdulrahman al-Rashed, the former general manager of the kingdom’s Al Arabiya News Channel, wrote of the bills passage by the U.S. congress: