The Pentagon is investigating what one of their Air Force WC-135 pilots called an ‘unprofessional’ maneuver when a pair of Chinese Su-30 fighter jets intercepted their aircraft last week. Known as a ‘sniffer’ the WC-135W Constant Phoenix is a specially equipped derivative of the C-135 aircraft with the mission of collecting samples from the atmosphere to detect nuclear explosions.

The issue is being addressed with China through appropriate diplomatic and military channels,” said U.S. Air Force spokeswoman Lieutenant Colonel Lori Hodge.

Hodge said the U.S. characterization of the incident was based on initial reports from the U.S. air crew aboard the WC-135 Constant Phoenix aircraft “due to the maneuvers by the Chinese pilot, as well as the speeds and proximity of both aircraft”.