The Transportation Security Administration is defending its operations at Newark Liberty Airport in New Jersey following a report last week that an undercover inspector sneaked a simulated explosive past security.

The TSA said Wednesday on its blog that it�s conducting tests that some officers are prone to fail – to improve performance and stay a step ahead of adversaries.

The New York Post reported Friday a tester got a mock improved explosive device in his pants through security, including a pat-down. It led a congressman to call for a full security review.

The TSA says test items are �extremely hard to spot,� not �a cartoonish bundle of dynamite with an alarm clock strapped to it.� It says the reported slipping of a mock IED past screeners tested just one of 20 layers of security.

(AP)