In March, Lieutenant General Brehon B. Somervell, head of the Army Service Forces, estimated that eight months after the date of approval, the plan would have a monthly output of 1,000 anthrax spore bombs, or 275,000 botulinum toxin bombs. He said that production on this scale would place the United States in a position to supply biological agents just when "the current timetable for operations in the Pacific would indicate our approach to the Japanese homeland."

However, General Somervell noted that the United States was committed to refrain from using poisonous gases or other inhumane devices of war, except in retaliation. He noted that General Marshall had supported a recommendation that biological warfare not be used against Germany or its satellites except in response to a similar attack.

Japan fell into a different category. General Marshall wanted plans made to use biological weapons against Japan following Germany's defeat, as General Somervell recalled, but had urged that no final decision be made prematurely.

General Somervell sought permission from the Joint Chiefs of Staff to produce offensive materials and develop measures by Jan. 1, 1946, for possible use against the Japanese home islands.

The British were engaged in a similar project; they had kept the Americans fully informed. In April 1944, Lord Ismay, chief of staff to Britain's defense minister, wrote to Field Marshall Sir John Dill, the British representative on the Combined Chiefs of Staff in Washington, that the United States hoped to inaugurate a plant soon that would produce bacteriological bombs at a rate of 25,000 to 50,000 a month. A much larger plant was also planned, he said, adding that Churchill had approved a proposal for Britain to place a preliminary order for 500,000 of these bombs.

Lord Ismay said that there could "of course, be no [underlined by him] question of either country using this form of warfare except by way of retaliation for its adoption by the enemy, and then only after consultation with one another."

The question of formulating a combined U.S.-British policy on the issue was considered but discarded. Nonetheless, General Marshall informed General Eisenhower by a top-secret signal that the U.S. Joint Chiefs of Staff had advised their British counterparts of their agreement that general information on bacteriological measures should be issued to medical and intelligence staff in the military forces of both nations. This was to prevent them being taken by surprise should the enemy launch a germ warfare attack.