Wartime coalitions usually unravel when the common threat is over. The demise of the Grand Alliance was unusual only in how rapidly one of the partners came to be regarded by the others as an adversary. At Yalta, Stalin had seemed reasonable, inclined to meet his allies partway on matters such as Poland. But Soviet behavior after the conference led US officials to question whether he valued cooperation or meant to get what he could. Soviet landings in the Kuriles raised speculation that the action represented the fulfillment of a secret accord. Stalin's radio announcement that the islands and the southern half of Sakhalin would become Soviet possessions added to the uncertainty. In a press conference on September 4, James E. Byrnes resorted to evasion. What has been referred to as "atomic diplomacy" consisted at most of a general feeling that respect for the newly acquired weapon would cause the Soviets to be accommodating.