Authorities are investigating how vandals could have slipped past security to spray-paint a $2.3 million Learjet at Van Nuys Airport.
The Los Angeles Times reports police believe the crime to be gang-related.
Airport police chief Patrick Gannon says the Learjet was parked in a secure area and vandals went to great lengths to get past security and access the airfield.
The plane was spray-painted with the word "flame" and several tags.
A union spokesman for security officers at local airports blamed attrition and staffing shortages that have gone unresolved for years.
Gannon confirmed there has been some attrition but says airport managers are willing to hire qualified officers.