The program to destroy America's chemical and nerve weapons has achieved a major milestone: the destruction of 45 percent of the stockpile. Deseret Chemical Depot in Utah's western desert incinerated the vast majority of the total.

According to a news release from the Army Chemical Materials Agency, the 45 percent mark was reached June 18, so the country met a deadline under the Chemical Weapons Convention.

Under the compact, which went into effect in 1997, the United States originally was to destroy 1 percent of its stockpile by April 2000; 20 percent by April 2002; 45 percent by April 2004; and 100 percent by April 2007.

The deadlines were subject to extensions. This country met the 2000 and 2002 deadlines, but not the original one of 25 percent by 2004. The deadline was extended to December 2007 by the Organisation for the Prohibition of Chemical Weapons.

In April 2006, according to the agency, the United States requested a five-year extension, allowed by the convention, on the deadline for 100 percent destruction. That would permit America to take until April 2012 to destroy all of the stockpile, the CMA reported.

"However, in its extension request letter," adds a release, "the United States notified the OPCW (Organisation for the Prohibition of Chemical Weapons) that it does not currently forecast 100 percent destruction by the new deadline, but remains committed to the accord and will complete its stockpile destruction under international observation as quickly as possible."

Asked why a 45 percent goal was set rather than the more common objective of 50 percent, Mickey Morales, public affairs officer for the Army Chemical Materials Agency in Maryland responded, "While round numbers, such as 50 percent, are appealing, the Organisation for the Prevention of Chemical Weapon has established this set of milestones (including the 45 percent goal) against which all state parties' destruction, including the United States, is measured."

He said 45 percent was chosen as "the result of negotiations in which the percentages selected had to correspond to a realistic time line for meeting them." He answered spoken questions via e-mail.

According to information Morales provided, America has destroyed almost 14,000 tons of chemical warfare agent since 1997. The specifics are:

• Aberdeen Proving Ground, one-ton containers of mustard agent, 1,622 tons. It destroyed its entire stockpile and the destruction plant is closed.

• Anniston Army Depot, Ala., 620 tons of VX and GB nerve agent contained in M55 rockets and projectiles.

• Blue Grass Army Depot, Ky, nothing yet destroyed — the destruction pilot plant is under construction.