Under existing law, the Treasury secretary, in consultation with the Federal Reserve chairman, secretary of state, federal regulators and other agencies, has the power to impose such restrictions on transactions. However, a public rulemaking notice must be issued with the restriction, and the restriction lifts after 120 days unless the Treasury Department implements a rule continuing the block after the comment period.
Source: https://www.coindesk.com/policy/2022/01/31/provision-in-house-bill-allowing-treasury-secretary-to-block-international-crypto-transactions-to-be-removed/