According to a United States official, long-range ballistics missiles sought by Ukraine have been delivered quietly by the U.S. and are being utilized on the battlefield against Russia almost a month after President Joe Biden pledged them to his Ukrainian counterpart.

The official, who spoke Tuesday on the condition of anonymity, was not authorized to publicly discuss the matter ahead of an official announcement.

Ukrainian President Volodymyr Zelenskyy, along with other Ukrainian leaders, had been urging the U.S. to provide the Army Tactical Missile System, known as ATACMS.

Delivery of the powerful weapons to the warfront was shrouded in secrecy, with the expectation the first public acknowledgement would come once the missiles were used on the battlefield.