Though historians continue to argue about the role of American nuclear threats in producing an armistice in the Korean War, by 1953 the United States was moving closer to actually escalating the war with the employment of atomic bombs. While military studies and unsatisfactory exercises during the first two years of the conflict had relegated such weapons to a role just as a last resort to prevent a catastrophe, frustration with stalemated peace talks and the aggressiveness of General Mark Clark combined to produce a set of contingencies envisioning an expanded war involving nuclear air strikes.