“What exactly they are doing? Left to be seen. These are things that we need to sort out,” Lloyd Austin was quoted as saying.
This is the second such package within a week, as Ukraine's defensive lines wear in the east.
U.S. President Joe Biden pledged to send Ukraine "hundreds" of air defense interceptors within months.
While staggering, the losses don't mean a clear victory for Ukraine either, U.S. officials said.
