Lost for 70 years, the C-47 aircraft was accidentally discovered in 2015 at a junkyard in Oshkosh, Wis.
Mattis said the U.S. and Russia are still using a phone line to coordinate flight movements over crowded Syrian skies.
A pilot has traced a virtual Christmas tree over Germany on a test flight with an Airbus A380.
A-10 Thunderbolts could be sent back to Afghanistan to bolster the air campaign.
The Marine Corps is investigating after yet another incident involving U.S. military aircraft in Japan.