Yes. As a practical matter, any IEP that sends chassis into the 50 States and the District of Columbia will have to mark those chassis as required by the IEP final rule (73 FR 76794). Otherwise, the motor carrier pulling the chassis/container combination would have violated the marking regulation (§ 390.21).
Because motor carriers are unlikely to accept the risk of fines for transporting unmarked chassis, foreign or non-‘United States’ IEPs that know their equipment will operate within the United States may find it necessary, for business reasons, to file a Form MCS-150C and mark their equipment. FMCSA will accept registration applications from such entities and issue them USDOT numbers. In these cases, however, the assignment of an identifying number does not amount to an assertion of jurisdiction over the foreign or non-United States IEP.