Washington (AP) -- The Pentagon has extended its timeline to destroy the nation's aging chemical weapons arsenal until 2023, despite concerns by Congress and watchdog groups. There is fear that the stockpiles raise the risk of an accident or theft by terrorists.

Part of the stockpile is at the Bluegrass Army Ammunition Depot near Richmond in Madison County.

The new schedule is outlined in Pentagon documents obtained by USA TODAY and show the military won't eliminate its stock of deadly nerve gases and skin-blistering agents until eleven years after the 2012 deadline set by the international Chemical Weapons Convention.

The US government had already asked for a five-year extension from an earlier 2007 deadline.

An 11 a.m. news conference is scheduled for Tuesday at the depot near Richmond.