India, Aug. 23 -- Iran's armed forces warned Gulf nations on Wednesday against assisting American military operations, hours after the United Arab Emirates announced it was severing economic ties with Tehran following renewed attacks on shipping, marking a sharp deterioration in a regional crisis that has simmered since fighting between Washington and Tehran first broke out in February.

Iranian armed forces chief of staff Ali Abdollahi said any support extended to US forces would be treated as direct participation in the conflict. "Any assistance or facilitation provided to the aggressor US military amounts to participation in the US military operation," Abdollahi said, according to Iran's semi-official Mehr news agency.

The warning cam...