International businesses selling to U.S. customers may be subject to economic nexus laws if they meet a specific state's revenue or transaction thresholds. Even without a physical presence in the U.S., these businesses might be required to collect and remit sales tax if their sales volume or number of transactions in a state exceeds the set thresholds. Compliance requires registering with state tax authorities and adhering to U.S. tax regulations, which can add complexity for international sellers.