The United States will send Ukraine another Patriot missile system, two U.S. officials said Tuesday, answering Kyiv’s desperate calls for more air defenses as it battles an intense Russian assault on the northeastern Kharkiv region.

The officials said President Joe Biden has approved the move. It would be the second Patriot system that the U.S. has given to Ukraine, although the Pentagon has routinely provided an undisclosed number of missiles for the system. Other allies, including Germany, also have provided air defense systems as well as munitions for them.

The two U.S. officials spoke on condition of anonymity because the decision has not been publicly announced. The decision was first reported by The New York Times.

Ukrainian President Volodymyr Zelenskyy late last month pleaded for additional U.S.-made Patriot systems, arguing that they will help his forces fight the close to 3,000 bombs that he said Russia launches into the country every month.