But the most pressing issue at hand is much older: It’s the September 11 attacks. As Obama prepares to travel, Congress is considering a bill that would open the door for Saudi interests to be held liable in court for the attacks. And as The New York Times reported over the weekend, the Saudi government is threatening to sell off nearly a trillion dollars in assets held in the U.S. if the bill passes.

The families of 9/11 victims have attempted to sue Saudi Arabia for playing a role in those attacks, but under a 1976 law, foreign governments are immune from many types of lawsuits in American courts. The bill under consideration now would tweak current law, so that foreign governments could be held liable if they are found culpable for attacks on U.S. soil that kill Americans. That very narrow scope—carefully calibrated to apply to few situations—could allow lawsuits to move forward.

The bill is unusually bipartisan, co-sponsored by members of both parties’ leadership teams: Democrat Chuck Schumer of New York, the presumptive leader when Senator Harry Reid retires, and Republican John Cornyn of Texas, the majority whip. It has the support of members from Ted Cruz to Chris Coons and Chuck Grassley to Kirsten Gillibrand. In the last couple of days, both Hillary Clinton and Senator Bernie Sanders, the Democratic presidential candidates, have said they support it. It passed through the Senate Judiciary Committee unanimously in February.

Notably, however, the Obama administration has opposed the bill. The White House has lobbied Congress not to pass the bill, and Press Secretary Josh Earnest threatened a presidential veto on Monday, saying, “It's difficult to imagine a scenario in which the president would sign the bill as currently drafted.” In February, Secretary of State John Kerry told senators that the bill would “create a terrible precedent” that could lead to other countries opening up the U.S. government to lawsuits, despite the carefully tailored language. The Times reports that top State and Defense Department officials warned lawmakers in a closed-door briefing that the law could expose American soldiers and diplomats abroad.

The Saudi threat to withdraw investments has gotten more attention than those cautions, though. The assets in question include $750 billion in Treasury notes, plus some other investments, which the government fears could be frozen by U.S. courts in a lawsuit. Saudi Foreign Minister Adel al-Jubeir reportedly delivered the threat in Washington in person. There’s a great deal of skepticism from economists and lawmakers about the threat, which could be damaging to the U.S. economy, but even worse for the Saudi economy, which has already been battered by the declining price of oil.

But wait, what role did Saudi Arabia play in the attacks? The 9/11 Commission report said this: “We have found no evidence that the Saudi government as an institution or senior Saudi officials individually funded the organization.” Just like the proposed change to sovereign foreign immunity, it’s a narrowly tailored sentence.