What is "winter hawk"

Winter Hawk is a 1987 thriller novel written by Craig Thomas. It is the novel set within a larger continuum linking many of Thomas’s other books, including some characters last seen in Firefox Down, itself a sequel to Thomas’s Firefox. Though the featured character is Mitchell Gant, the plot is composed of several running subplots surrounding the imminent launch of the Soviets’ Space Shuttle and the planned signing of an historic arms reduction treaty between the United States of America and the Soviet Union.