If the Senate ratifies the CWC, moreover, the administration has announced that it intends to interpret the treaty so broadly as to deny American troops the use of humane, nonlethal weapons like tear gas -- which are likely to come in handy in places like Haiti.
The Iraqi declaration is said to lack any explanation for what has happened to certain equipment and arms, such as shells filled with mustard gas, that had remained unaccounted for even when weapons inspectors were last in Iraq in the late 1990s.
Another might be fear that the aliens would retaliate with even more devastating weapons, in the same way that no one used poison gas in World War II for fear of the consequences.