On Tuesday at noon, President Obama is unveiling his plan for drastically scaling back the presence and threat of nuclear arms across the globe. He has previewed the Nuclear Posture Review (as the White House calls it) with reporters ahead of time. Obama has long emphasized his aim  to reduce the number of nuclear weapons in the United States and elsewhere. Here's what's in the plan, what it means, and some judgments on whether it's any good.

• What's in The Plan  The New York Times' David Sanger and Peter Baker explain, "Obama described his policy as part of a broader effort to edge the world toward making nuclear weapons obsolete, and to create incentives for countries to give up any nuclear ambitions. To set an example, the new strategy renounces the development of any new nuclear weapons, overruling the initial position of his own defense secretary. Mr. Obama’s strategy is a sharp shift from those of his predecessors and seeks to revamp the nation’s nuclear posture for a new age in which rogue states and terrorist organizations are greater threats than traditional powers like Russia and China."

• 'Sole' Purpose of Nukes: Deterrence  Self-declared "arms control wonk" Jeffrey Lewis tweets, "Looks like the NPR [Nuclear Posture Review]  will embrace the 'fundamental purpose' of nukes is to deter nukes; will work to create conditions to say 'sole' purpose." The New York Times' Sanger and Baker elaborate, "For the first time, the United States is explicitly committing not to use nuclear weapons against nonnuclear states that are in compliance with the Nuclear Nonproliferation Treaty, even if they attacked the United States with biological or chemical weapons or launched a crippling cyberattack."

• Except With Rogue States--But Who Determines That?  Conservative blogger William Jacobson notes that the NPR allows nukes to be used against states that violate the Nuclear Nonproliferation Treaty. But who, he asks, determines the violators? The U.N.? President Obama? "What if the country in question disputes 'alleged' non-compliance? Shouldn't the people of that country be entitled to some measure of due process?"

• Clarifying Our Policy Makes Us Weaker  Commentary's Jennifer Rubins balks, "Why foreswear defensive use of nuclear force? Why remove strategic ambiguity?" She argues that, by keeping our nuclear policy ambiguous, it makes potential enemies second-guess any action that could potentially provoke a nuclear response.

• Emphasizes Nukes Over Nuke-Wielding States  Spencer Ackerman sees Obama's plan as "declaring that the principle nuclear threat to the U.S. is from proliferation — that is, not just from a nuclear-armed enemy, but from the existence of the weapons themselves." That places the emphasis on reducing the number of nuclear weapons rather than constraining the states that possess nuclear weapons.

• Too Tough on Iran?  Flynt and Hillary Mann Leverett read the review as giving the U.S. "the prerogative to use nuclear weapons against the Islamic Republic of Iran, even as Iran remains a non-nuclear-weapons state. [...] More specifically, the Administration will reserve the prerogative for the United States to use nuclear weapons first, at its discretion, against non-nuclear-weapons states that are not, in Washington’s view, in full compliance with their obligations under the Nuclear Non-Proliferation Treaty (NPT)."

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