The US President can unilaterally declare the US will not pay its bonds held by China or cut off capital in other ways.

Test: whether, as of 2020-10-25, US law gave the President authority to act without new legislation to (a) block, freeze or withhold payments on US Treasury securities held by a foreign government such as China, and (b) restrict capital flows in other ways, for example under IEEPA emergency powers. True: legal authorities and precedent (such as asset freezes against foreign governments) confirm both. Mostly true: (b) is clearly available and (a) is available as blocking or freezing payments rather than outright repudiation. Mixed: one of the two is clearly available and the other is legally contested, for example because of the 14th Amendment public-debt clause. Mostly false: both are available only with significant legal doubt or with congressional action. False: the President has no such unilateral authority.

Set before the research began.

1. E1 Levers of Default: Can the President Unilaterally Alter the Terms of the National Debt? - Penn Law Review Penn Law Review · 24 March 2026

   “Our analysis finds that although the President lacks authority to change the terms of outstanding debt retroactively, the President can accomplish similar goals by issuing new debt instruments that embed unprecedented powers.”

2. E2 Levers of Default: Can the President Unilaterally Alter the Terms of the National Debt? - Penn Law Review Penn Law Review · 24 March 2026

   “These provisions likely bar the United States from altering the terms of its national debt unilaterally, but the sole U.S. Supreme Court decision to address the question”

3. E3 Levers of Default: Can the President Unilaterally Alter the Terms of the National Debt? - Penn Law Review Penn Law Review · 24 March 2026

   “Although the President cannot alter the terms of current treasuries ex post, nothing stops the government from issuing new treasuries granting such power ex ante.”

4. E4 Levers of Default: Can the President Unilaterally Alter the Terms of the National Debt? - Penn Law Review Penn Law Review · 24 March 2026

   “Our analysis finds that although the President lacks authority to change the terms of outstanding debt retroactively, the President can accomplish similar goals by issuing new debt instruments that embed unprecedented powers.”

5. E5 Levers of Default: Can the President Unilaterally Alter the Terms of the National Debt? - Penn Law Review Penn Law Review · 24 March 2026

   “Precisely because the President lacks the authority to alter the terms of already issued treasuries, any exercise of such a right—while technically legal—would be treated as a sovereign default and have unforeseeable (and possibly catastrophic) consequences for the U.S. economy and the global financial system.”

6. E6 PERRY v. UNITED STATES, 294 U.S. 330 (1935) | FindLaw FindLaw (reporting the U.S. Supreme Court opinion) · 1935

   “We conclude that the Joint Resolution of June 5, 1933, in so far as it attempted to override the obligation created by the bond in suit, went beyond the congressional power.”

7. E7 PERRY v. UNITED STATES, 294 U.S. 330 (1935) | FindLaw FindLaw (reporting the U.S. Supreme Court opinion) · 1935

   “Because the government is not at liberty to alter or repudiate its obligations, it does not follow that the claim advanced by the plaintiff should be sustained.”

8. E8 PERRY v. UNITED STATES, 294 U.S. 330 (1935) | FindLaw FindLaw (reporting the U.S. Supreme Court opinion) · 1935

   “Nor can we perceive any reason for not considering the expression 'the validity of the public debt' as embracing whatever concerns the integrity of the public obligations.”

9. E9 PERRY v. UNITED STATES, 294 U.S. 330 (1935) | FindLaw FindLaw (reporting the U.S. Supreme Court opinion) · 1935

   “The Congress had authorized the prohibition of the exportation of gold coin and the placing of restrictions upon transactions in foreign exchange.”

The Penn Law Review essay (E1–E5) concludes that the President lacks authority to change the terms of outstanding Treasuries after the fact, and Perry v. United States (E6–E8) holds that the government is not at liberty to alter or repudiate its obligations. Both point against outright repudiation. None of the evidence says whether, as of 2020, the President could freeze or block payments to a particular foreign holder such as China. On part (b), nothing covers IEEPA or other present-day emergency powers to restrict capital: E9 only mentions earlier gold-export and foreign-exchange restrictions, and it says Congress authorised them [E9]. The criteria require both parts to be assessed, and the evidence does not settle either one well enough to pick a verdict.