The largest U.S.-based cryptocurrency exchange, which on Thursday filed to go public with the Securities and Exchange Commission, in a regulatory filing said it has submitted disclosures to or responded to administrative subpoenas from the U.S. Treasury Department’s Office of Foreign Assets Control, or OFAC, which enforces U.S. sanctions.

The company in its prospectus, filed to the SEC last week, said it hasn’t faced monetary penalties or other enforcement actions related to the disclosures or subpoenas, but that some of its disclosures are still under review by OFAC.

U.S. regulations prohibit transactions with blacklisted individuals or companies and with governments or jurisdictions subject to comprehensive U.S. sanctions.

The nature of blockchain technology and Coinbase’s services make it “technically infeasible” to prevent transactions with certain individuals or companies or addresses, the company said.

A spokesman for Coinbase declined to comment. A spokeswoman for the Treasury said the department doesn’t comment on investigations, nor does it confirm whether or not one exists.