A preventive war or preventative war is a war initiated to prevent another party from acquiring a capability for attacking. The power being attacked has either a latent threat capability or has shown through its posturing that it intends to follow suit with a future attack. Preventive war aims to forestall a shift in the balance of power by strategically attacking before the balance of power has a chance to shift in the direction of the adversary. Preventive war is distinct from preemptive war, which is first strike when an attack is imminent. Preventive war undertaken without the approval of the United Nations is illegal under the modern framework of international law, though Robert Delahunty and John Yoo from the George W. Bush administration maintained in their discussion of the Bush Doctrine that these standards are unrealistic.