The United States has quietly delivered the long-range ballistic missiles that Ukraine said it urgently needed and that President Joe Biden promised last month, U.S. officials said Tuesday, and Ukraine has already begun using them on the battlefield against Russia for the first time.

The missiles arrived in Ukraine within the last few days, one of the officials said. Their delivery to the warfront gives Ukraine a critical ability to strike Russian targets that are farther away, allowing Ukrainian forces to stay safely out of range. The officials were not authorized to publicly discuss the matter before an official announcement and spoke Tuesday on the condition of anonymity.

The delivery of the Army Tactical Missile System, known as ATACMS, was shrouded in secrecy, with the expectation that the first public acknowledgement would come when the missiles were used on the battlefield. That intense secrecy is a marked change from previous U.S. weapons sent by the Biden administration. In nearly all other cases, the U.S. has publicly announced its decision prior to the weapons and equipment being shipped overseas.