The ongoing controversy over weapons of mass destruction in Iraq has again been in the spotlight on Capitol Hill. A congressional hearing (Thursday) heard from U.S. military officials and experts about chemical munitions discovered in Iraq since 2003.

The term Weapons of mass destruction (WMD) may seem to many people simple to define, but Thursday's hearing showed once again the extent to which the exact definition has become a political football since the U.S. invaded Iraq in 2003.

According to declassified portions of a report by the U.S. Army's National Ground Intelligence Center 500 rocket and artillery shells discovered in Iraq contained either the deadly nerve agent sarin, or mustard gas - both of which can cause serious injury and death.

In making details of the report public recently, two Republican lawmakers, Senator Rick Santorum and Congressman Pete Hoekstra, pointed to it as further justification for U.S. and coalition military action in Iraq.

But critics dismissed the information, saying the type of munitions and their age, dating back to the 1980's and Iraq's war with Iran, don't even come close to fitting the WMD definition that many Americans believed formed the basis for war in Iraq.

The Republican chairman of the House Armed Services Committee, Duncan Hunter, used his opening statement to describe what he said was the purpose of the hearing.

"Tell us what you have, without embellishment, without conclusions, without editorials, but very simply, just the facts," said Duncan Hunter.

However, the hearing was largely an attempt by majority Republicans to underscore their contention that WMD were always present in Iraq.

Curt Weldon is a Pennsylvania Republican:

"We now have verified the existence of about 500 such weapons and the intelligence report assesses that others, ones that could be sold on the black market, that could fall into the hands of terrorist or insurgents, that could end up outside of Iraq, exist there," said Curt Weldon.

Lieutenant General Michael Maples, head of the Defense Intelligence Agency, testified that although in degraded condition, the munitions found and the substances they contained posed, on their own, a potential risk to U.S. forces, and were vulnerable to falling into the hands of terrorists.

"They would represent a danger in Iraq for those who could come in contact with them or if they fell into the hands of others potentially they could become a threat either within Iraq, and I believe as the Director of National Intelligence stated, the possibility of use outside of Iraq could not be ruled out," said General Maples.

Army Colonel John Chiu expanded.

"Regardless of the purity of the sample, any remaining agent [in the shells] is toxic, with potential to be lethal," said Colonel Chiu.

However, Democratic lawmakers on the committee contended there is a big difference between the impression President Bush and administration officials gave about a possible imminent threat from Iraqi WMD development in the months before the U.S. invasion, and the munitions found since 2003.

Democratic lawmakers Susan Davis and Jim Cooper:

DAVIS: "It is very difficult to characterize these as these imminent threat weapons that we were told we were looking for, and that Saddam had."

COOPER: "I hate to see our nation's military used for the political gain of one party."

Former Iraq weapons inspector David Kay, who caused controversy in 2004 when he said no weapons of mass destruction had been found in Iraq, says discovery of chemical munitions in Iraq should come as no surprise.

He had this exchange with Ike Skelton, the top Democrat on the Arms Services Committee:

SKELTON: "Was there evidence of stockpiles of at least 100 metric tons or as much as 500 metric tons of chemical agents?"

KAY: "No, there was no evidence found of that."

However, Frank Gaffney, a former defense official known for his hawkish views on Iraq, and now heading the Center for Security Policy, asserts there can no doubt about WMD in Iraq.

"Whatever the derivation of this word was, in the current political parlance of this country, these weapons were weapons of mass destruction," said Frank Gaffney. "There remain WMD, I think almost certainly in considerable numbers in Iraq that could conceivably have some terrorist application."

Thursday's public hearing of the Armed Services Committee was followed by a classified hearing behind closed doors, where military officials said they could provide lawmakers with further details regarding the 500 chemical shells found in Iraq.