According to KYW News Radio 1060:
Union Says USPS Is Cutting Security Short by Cutting Officers

“The union representing Postal Police accuses the Postal Service of turning a blind eye to security.  While many businesses have increased security since the 911 and  anthrax attacks, the Postal Service has been cutting back.  So says John Dukes, President of the Fraternal Order of Police, Labor Council #2. “Well, we had over 14 hundred postal police positions before 911. And we just went down to 700 throughout the country.”  In Philadelpiha, the number of postal  police officers has fallen from more than 70 in 1999 to 39. Dukes says another round of firings will reduce the local force to 15 as of October first.   Why? “What they tell us is the postal police positions, through technology and all now, that they actually don’t need the positions.” But Dukes believes the Postal Service is merely cutting corners, with little regard for safety.”

Related links:

Despite Risk, Postal Service to Eliminate Police in Six Cities (2003)

Fraternal Order of Police - NLC #2 website