against a conventional attack. Although this strategy was revised, they both reserved the right to use nuclear weapons first under the new doctrine of "flexible response." The US doctrine for the use of nuclear weapons was revised most recently in the Nuclear Posture Review, released April 6, 2010. The 2010 Nuclear Posture Review reduces the role of U.S. nuclear weapons: "The fundamental role of U.S. nuclear weapons, which will continue as long as nuclear weapons exist, is to deter nuclear attack on the United States, our allies, and partners." The U.S. doctrine also includes the following assurance to other states: "The United States will not use or threaten to use nuclear weapons against non-nuclear weapons states that are party to the NPT and in compliance with their nuclear non-proliferation obligations." For states eligible for the assurance, the United States would not use nuclear weapons in response to a chemical or biological attack but states that those responsible for such an attack would be held accountable and would face the prospect of a devastating conventional military response. Even for states that are not eligible for the assurance, the United States would consider the use of nuclear weapons only in extreme circumstances to defend the vital interests of the United States or its allies and partners. The Nuclear Posture Review also notes, "It is in the U.S. interest and that of all other nations that the nearly 65-year record of nuclear non-use be extended forever." This supersedes the doctrine of the George W. Bush administration set forth in "Doctrine for Joint Nuclear Operations" and written under the direction of Air Force General Richard Myers, chairman of the Joint Chiefs of Staff. The new doctrine envisions commanders requesting presidential approval to use nuclear weapons to preempt an attack by a nation or a terrorist group using weapons of mass destruction. The draft also includes the option of using nuclear weapons to destroy known enemy stockpiles of nuclear, biological, or chemical weapons. In August 2016, President Barack Obama reportedly considered adopting a 'No First Use' policy. Obama was persuaded by several Cabinet officials such as Secretary of State John Kerry, Secretary of Defense Ash Carter, and Secretary of Energy Ernest Moniz that 'No First Use' would rattle U.S. allies and decided not to take up the policy. During the 2017–2018 North Korea crisis, there were efforts to either require congressional approval for a pre-emptive