>> i'm alison kosik. it is 30 minutes past the hour. president trump scouring for a new secretary of defense. james mattis will leave at the end of february. he tendered his resignation a day after the president revealed plans to withdrawal u.s. troops from syria. his departure shaking washington and creating uncertainty at the pentagon and at military bases around the world. >> mattis' resignation is a rebuke to the president's foreign policy views. mattis using his letter to promote the importance of u.s. alliance and unambiguous approach to russia and china. the last straw was the planned withdrawal from syria. for more, here is barbara starr at the pentagon. >> reporter: alison and dave, an administration official tells