Under pressure to prevent people from sneaking onto runways and planes at major U.S. airports, authorities are cracking down — not on the intruders who slip through perimeter gates or jump over fences, but on the release of information about the breaches.

A year after an Associated Press investigation first revealed persistent problems with airports’ outer defenses, breaches remain as frequent as ever — occurring about once every 10 days — despite some investments to fortify the nation’s airfields. As Americans focus on the wait in ever-longer security screening lines inside terminals, new documents show dozens more incidents happening outside perimeters than airports have disclosed.

At the same time, leaders at some airports and the U.S. Transportation Security Administration are saying some of the 345 incidents AP found shouldn’t count as security breaches, even when intruders got deep into secure areas.

Was it a perimeter security breach in March 2015 when a woman walked past a vehicle exit gate at San Francisco International Airport and onto the tarmac, where she tried to flag down a jet for a trip home to Guatemala? No it was not, said the airport and TSA officials, who also tried to suppress information about the case. Nor did they label it a breach when a man, following voices only he could hear, drove through a San Francisco security gate and asked a worker fueling a plane when the next flight was.

After discussing intrusions openly at first, officials at several airports and the TSA started withholding details, arguing the release could expose vulnerabilities. Following a two-year legal struggle with the TSA, AP has now used newly released information to create the most comprehensive public tally of breaches.

The count shows that an intruder broke through the security surrounding one of 31 major U.S. airports on average every 13 days from the beginning of 2004 through mid-February; since 2012, the average has been every 9.5 days. Many intruders scaled barbed wire-topped fences or walked past vehicle checkpoints. Others crashed cars into chain link and concrete barriers. AP’s tally is of breaches at airports that handle three-quarters of U.S. passengers; it’s an undercount, because several airports refused to provide complete information.

While several intruders had guns or knives, the TSA and airports have been more focused on stopping weapons that passengers or baggage handlers try to sneak onto planes.

“It doesn’t surprise me that people sometimes try to jump over fences to see what they can get away with,” TSA Administrator Peter Neffenger said in a brief interview. It’s impossible for airports and local law enforcement to keep everyone out, he said, so “the question is: What’s your ability to detect it and … what might you do to mitigate that happening in the future?”