The Veterans for Peace group said Thursday that on July 19 it "issued a call to all American generals to uphold their oath to defend the Constitution, an oath which requires officers and commanders to respect the treaties and laws for which American troops risk their lives."

The group said it had produced an open letter on the illegality of pre-emptive war that stated: "A commander who knowingly orders troops to participate in crimes against peace betrays himself and those who serve under him or her."

Veterans for Peace said the letter would be sent, along with copies of the Constitution of the United States, the United Nations Charter, the Nuremberg Conventions and the U.S. Army Field Manual, which upholds the right to disobey illegal orders, to commanding generals at U.S. military bases.

"The U.S. military is passing through a crisis of integrity," the group said in a statement. "Retired generals openly denounce the folly of the occupation. The number of GI war-resisters grows. Time magazine runs a cover story on low morale in the U.S. Army."

Created in 1985, Veterans For Peace describes itself as the largest anti-war veterans organization in the United States.