Retired Marine Corps General James Cartwright, a former head of U.S. Strategic Command and former deputy chairman of the Joint Chiefs of Staff, has argued 900 nuclear warheads in total - both deployed and in storage - is enough for deterrence.

Many observers believe the administration ultimately will settle on a figure of between 900 and 1,000 deployed warheads. Whatever the figure, the decision is Obama’s best opportunity to influence U.S. nuclear policy going forward.

“If he is committed to the vision that he outlined in Prague, what he should be doing here is telling the Pentagon that the role of nuclear weapons shall be restricted to deterring nuclear attack on the United States or its allies,” said Daryl Kimball, executive director of the Arms Control Association. “To do that we only need a nuclear force in the hundreds of deployed nuclear weapons, not the thousands.”