Newport -- Destruction of the chemical agent VX was halted Thursday after degraded valve seals were found during routine maintenance on one of two reactors used to neutralize the chemical at the Army's Newport Chemical Depot.

The second reactor, in which VX still was being processed, also was halted as a precaution.

The eroded seals, found on an internal three-way valve during routine maintenance, probably would not have caused an external leak. But they could have caused the agent to leak between the reactors, Army project manager Jeff Brubaker said in a written statement.

Replacement of the valve on the first reactor should be completed by the end of next week, when it will be put back in service while the second reactor's valve is replaced, spokeswoman Terry Arthur said.

VX, so lethal that a single drop could kill a person in minutes, was manufactured in Newport in the 1960s during the Cold War. Since 1969, more than 250,000 gallons of VX have been stored in carbonized steel containers at the western Indiana depot.

About 15 percent of the stockpile has been destroyed since last year with a mixture of water and sodium hydroxide.