LOS ANGELES (CBS) — Southwest Airlines has confirmed to KNX 1070 that pictures appearing on the website Gawker are consistent with the markings it has seen on some planes dating back to February 2011.

Source told KNX’s Charles Feldman that some people believed the markings looked like Arabic letters or symbols.

READ MORE: Ed Sheeran Tests Positive For COVID-19, Cancels In-Person Appearances

A British newspaper says one university’s department of Arabic studies concluded the markings are not Arabic script.

READ MORE: 'Supercharge' Storm Expected To Bring Heavy Rainfall To Southland

The markings seen by KNX investigators could be interpreted as crossed “X’s” or as sword-like symbols.

MORE NEWS: Man Fatally Shot In Unincorporated LA; Probe Underway

Southwest calls the writings vandalism, but says federal authorities have concluded the markings have no affiliation to any known group or activity.