In April 1970, in response to the Nixon administration's choice to back efforts by the South Vietnamese in Cambodia, senators made moves toward ending funding for American military aid there. Stennis and Michigan Senator Robert P. Griffin described the operation as one limited in scale and with the purpose of destroying sanctuaries of the North Vietnamese and Vietcong in Cambodia on the South Vietnam border. In July, Stennis advocated for the United States adopting an ABM system to safeguard against Soviet SS‐9 intercontinental ballistics missiles and called on fellow senators to recall "the grim fact of rapidly increasing Russian strategic forces which could place this country in jeopardy in the years ahead." In August, as the Senate voted to bar the United States from paying larger allowances to allied troops in Vietnam than it pays to American soldiers, Stennis said he was impressed with the legislation and that he would be in favor if "some adjustment can be made consistent with our honor". Stennis also pledged to try arranging an agreement between the two chambers on the final military procurement bill. Stennis furthered that the United States "would have to observe any commitments it might have already made, and that some delicacy might be necessary since American forces are leaving Vietnam." In September, the Senate voted on the McGovern–Hatfield Amendment, a proposal that would have required the end of military operations in Vietnam by December 31, 1970 and a complete withdrawal of American forces halfway through the next year. Stennis argued the amendment was constitutional and that Congress had "the sole power to appropriate money". The amendment was defeated in a vote of 55 to 39.