Eagle was appointed Shadow Secretary of State for Defence in September 2015 by the newly elected Labour leader Jeremy Corbyn. Eagle said she was surprised by her appointment as she had disagreed with Corbyn's advocacy of unilateral nuclear disarmament and supported the renewal of the Trident nuclear weapons system. Tasked with leading Labour's defence review, she said she would not rule out the possibility of it recommending unilateral disarmament. However, she described Corbyn commenting he would not countenance using a nuclear deterrent as "unhelpful" to the policy process.