The US Patent and Trademark Office (USPTO) has recent announced that as from August 3rd, 2019, foreign filers for trademarks must file through a registered US licensed Attorney. This will apply to all right holders, filing at the Trademark Office or appearing before the Trademark Board, which the permanent legal residences or principal place of business is outside the USA. The main aim of this new rule is to ensure accuracy and integrity at the register and to fight against fraudulent filings.
On a final note, this rule does not apply to international trademark applications filed through the Madrid Protocol and extended to the US. However, post-application and further prosecution of these applications should be handled by a US Attorney.