Defense attorneys for a man accused of plotting a suicide bomb attack at a Wichita airport are not being allowed to see some classified evidence.

U.S. District Judge Monti Belot issued a protective order Wednesday after examining the materials outside the presence of attorneys for Terry Loewen, an avionics technician who is accused of trying to drive a van filled with inert explosives onto the tarmac at Mid-Continent Airport in December 2013.

The judge says disclosure could cause serious damage to the national security. Belot also found none of the information was exculpatory, or favorable to the defendant.

Loewen has pleaded not guilty to attempting to use a weapon of mass destruction, attempting to use an explosive device to damage property and attempting to give material support to al-Qaida.