By 1962, the American government was becoming increasingly concerned at the lack of a commitment from Canada to take nuclear weapons. The interceptors and Bomarc missiles with which Canada was being supplied as a NORAD member were either of no use or of greatly diminished utility without nuclear devices. Canadian and American military officers launched a quiet campaign to make this known to the press, and to advocate Canadian agreement to acquire the warheads. Diefenbaker was also upset when Pearson was invited to the White House for a dinner for Nobel Prize winners in April, and met with the President privately for 40 minutes. When the Prime Minister met with retiring American Ambassador Livingston Merchant, he angrily disclosed the paper Kennedy had left behind, and hinted that he might make use of it in the upcoming election campaign. Merchant's report caused consternation in Washington, and the ambassador was sent back to see Diefenbaker again. This time, he found Diefenbaker calm, and the Prime Minister pledged not to use the memo, and to give Merchant advance word if he changed his mind. Canada appointed a new ambassador to Washington, Charles Ritchie, who on arrival received a cool reception from Kennedy and found that the squabble was affecting progress on a number of issues.