Leaked photos of a fifth generation stealth fighter plane being built by China have raised eyebrows around the world as to how the quickly China's aviation program is advancing ahead of schedule.
The photographs, of what appears to be a prototype J-20 jet undergoing runway tests, has been circulating on the internet since last week.
Aviation websites said the photos were taken from outside a fence at the Chengdu Aircraft Design Institute's airfield in southwestern China.
Wednesday, Chinese government run media ran articles on the photos.
Adding validity to claims the country's military aviation program is far ahead of schedule.
However, the U.S. Defense Department said it wasn't concerned about the reports.
"It is not of concern that they are working on a fifth-generation fighter," Marine Col. Dave Lapan, a Pentagon spokesman, said, since the Chinese are "still having difficulties with their fourth-generation fighter."
Analysis of the J-20 photos shows it to be larger than either the Russian or U.S. planes, likely allowing it fly farther and carry heavier weapons.
Check out the photos below.