While oil’s collapse has deepened concern that Saudi Arabia will need to liquidate its Treasuries to raise cash, a more troubling worry has also emerged: the specter of the kingdom using its outsize position in the world’s most important debt market as a political weapon, much as it did with oil in the 1970s.

In April, Saudi Arabia warned it would start selling as much as $750 billion in Treasuries and other assets if Congress passes a bill allowing the kingdom to be held liable in U.S. courts for the Sept. 11 terrorist attacks, according to the New York Times. The threat comes amid a renewed push by presidential candidates and legislators from both the Democratic and Republican parties to declassify a 28-page section of a 2004 U.S. government report that is believed to detail possible Saudi connections to the attacks. The bill, which passed the Senate on May 17, is now in the House of Representatives.

Saudi Arabia’s Finance Ministry declined to comment on the potential selling of Treasuries in response. The Saudi Arabian Monetary Agency didn’t immediately answer requests for details on the total size of its U.S. government debt holdings.

“Let’s not assume they’re bluffing” about threatening to retaliate, said Marc Chandler, the global head of currency strategy at Brown Brothers Harriman. “The Saudis are under a lot of pressure. I’d say that we don’t do ourselves justice if we underestimate our liabilities” to big holders.

Saudi Arabia, which has long provided free health care, gasoline subsidies, and routine pay raises to its citizens with its petroleum wealth, already faces a brutal fiscal crisis.

In the past year alone, the monetary authority has burned through $111 billion of reserves to plug its biggest budget deficit in a quarter-century, pay for costly wars to defeat the Islamic State, and wage proxy campaigns against Iran. Though oil has stabilized at about $50 a barrel (from less than $30 earlier this year), it’s still far below the heady years of $100-a-barrel crude.

Saudi Arabia’s situation has become so acute the kingdom is now selling a piece of its crown jewel—state oil company Saudi Aramco.

What’s more, the commitment to the decades-old policy of “interdependence” between the U.S. and Saudi Arabia, which arose from Simon’s debt deal and ultimately bound together two nations that share few common values, is showing signs of fraying. America has taken tentative steps toward a rapprochement with Iran, highlighted by President Barack Obama’s landmark nuclear deal last year. The U.S. shale boom has also made America far less reliant on Saudi oil.

“Buying bonds and all that was a strategy to recycle petrodollars back into the U.S.,” said David Ottaway, a Middle East fellow at the Woodrow Wilson International Center in Washington. But politically, “it’s always been an ambiguous, constrained relationship.”

Yet back in 1974, forging that relationship (and the secrecy that it required) was a no-brainer, according to Parsky, who is now chairman of Aurora Capital Group, a private equity firm in Los Angeles. Many of America’s allies, including the U.K. and Japan, were also deeply dependent on Saudi oil and quietly vying to get the kingdom to reinvest money back into their own economies.

“Everyone—in the U.S., France, Britain, Japan—was trying to get their fingers in the Saudis’ pockets,” said Gordon S. Brown, an economic officer with the State Department at the U.S. embassy in Riyadh from 1976 to 1978.