On Tuesday, we covered reaction to Obama's new nuclear strategy, to be unveiled today at noon. This morning, an op-ed from vice president Joe Biden appears in the Los Angeles Times, explaining what's in the plan, why it's there, and why these changes are a good idea. Here's the breakdown.

HOW THIS PLAN MODERNIZES AMERICA'S NUCLEAR STRATEGY

This new strategy, a sharp departure from previous Nuclear Posture Reviews released in 2001 and 1994, leaves Cold War thinking behind. It recognizes that the greatest threat to U.S. and global security is no longer a nuclear exchange between nations, but nuclear terrorism by extremists and the spread of nuclear weapons to an increasing number of states.

WHAT THE CHANGES ARE, AND WHY THEY'RE THERE

The review contains a clear rationale for the reductions called for under the New START treaty--a 30% reduction from the previous agreement. Because of advances in conventional capabilities and technologies such as missile defense, we need fewer nuclear weapons to deter adversaries and protect our allies than we did even a decade ago. ...

The plan also establishes a policy that the United States will not use or threaten to use nuclear weapons against non-nuclear states, as long as they are party to the Nuclear Nonproliferation Treaty and in compliance with their nuclear nonproliferation obligations.

HOW THE PRESIDENT INTENDS TO KEEP THE NUCLEAR PROGRAM STRONG

At the same time, the president is determined to ensure that our nuclear weapons remain absolutely safe, secure and effective. That is why he has asked Congress to increase funding for our nuclear complex by $5 billion over the next five years, allowing us to upgrade aging facilities and recruit and retain the highly skilled scientists and engineers needed to sustain our arsenal. Our plan reverses a decade-long erosion in support for the national laboratories. This commitment will ensure that our arsenal remains ready.