The Osprey is back in the air after being grounded following a crash that killed eight U.S. troops in Japan, but questions remain about its safety.
Austin praised women in the military and said they should not be removed from front-line fighting posts.
The latest tranche of weapons comes as worries grow about an escalation in the conflict.
The use of the long-range missiles came as Russian President Vladimir Putin formally lowered the threshold for using nuclear weapons.
