This is the week the Obama White House goes nuclear.
Not nuclear power, but nuclear weapons. Today's announcement of the Nuclear Posture Review begins a series of nuclear weapons reduction related activities.
The review states that the U.S. will not use nuclear weapons against a non-nuclear country or in response to a chemical or biological attack.
But, the review allows for reasons for nuclear use, specifically if a country passes nuclear weapons to a terrorist group. Overall, the review bolsters the Obama Administration's efforts to rid the world of nuclear weapons.
Last year in Prague, in a major policy speech on his first foreign trip, Mr. Obama laid out his vision: "I state clearly and with conviction America's commitment to seek the peace and security of a world without nuclear weapons."
In that April 5, 2009, speech, he said America has a responsibility to act. He said: "And as a nuclear power - as the only nuclear power to have used a nuclear weapon - the United States has a moral responsibility to act. We cannot succeed in this endeavor alone, but we can lead it." (Read the text of that speech here.)
On Thursday, the president is scheduled to go back to Prague, this time to sign the new START treaty with Russian President Dmitri Medvedev. The treaty, a follow-up to the 1991 START Treaty - will further reduce the nuclear weapons stockpile of the two former Cold War foes, setting a new limit of 1,550 deployed warheads, down from the 2200 currently allowed under other treaties.
Heralding the agreement on the new treaty, which he began negotiating with the Russians last July in Moscow, the president called it.
"Today, we've taken another step forward by -- in leaving behind the legacy of the 20th century while building a more secure future for our children," he said at the White House in March.
Steven Pifer, a former Ambassador to Ukraine and former National Security Council expert on arms control said the treaty will keep important verification rules in place allowing the U.S. to monitor and account for Russia's nuclear stockpiles, but will also give the U.S. a boost in the bigger effort to convince other nuclear powers to reduce weapons. The most important goal of all of this is to prevent states that desire nuclear weapons, Iran specifically, from obtaining them.
"Hopefully this gives a boost not only to our efforts to pursue nonproliferation, that this is an example we can use to get other countries to try and curb the attempts by countries that don't have nuclear weapons to acquire them. But also this may be a stepping stone to even further reductions," said Pifer, now with the Brookings Institution in Washington.
Shortly after the treaty is signed, the president heads back to Washington where he will be joined next week by the leaders of at least 40 other countries in a nuclear security summit.
Mr. Obama himself has described this event as "a summit to address how we can secure vulnerable nuclear materials so that they never fall into the hands of terrorists." The focus will be securing nuclear materials, from power plants, research reactors and weapons themselves in four years.
Quietly, this has been a major project for the U.S. government since the attacks of 9/11. The Energy Department's National Nuclear Security Administration has led the way, working with other countries to safeguard weapons.
Since 2001, the NNSA has upgraded the security at 73 Russian nuclear warhead sites. It has also recovered enough highly enriched uranium to make more 80 nuclear weapons from sites around the world. Additionally, the NNSA has helped to reduce the world's reliance on weapons-grade highly enriched uranium in nuclear power by converting 57 research reactors to low-enriched, non-weapons ready, uranium. The agency has also provided security for 18 civilian power reactors worldwide.
(At left: check out this exclusive CBS News report on the NNSA from 2007.)
After this nuclear week wraps up, the next event on the schedule is in May when the president is expected to take part in a conference on the Nuclear Nonproliferation Treaty, aiming to provide tough sanctions on countries who develop nuclear weapons.
Rather simply, Secretary of State Hillary Clinton summed up the administration's focus on a nuclear weapons free world: "It is one of the highest priorities of the Obama administration to pursue an agenda to reduce the threat posed by the deadliest weapons the world has ever known."
Robert Hendin is a CBS News White House producer. You can read more of his posts in Hotsheet here.