President Obama has said that the United States won't use nuclear weapons against states with no nuclear weapons that are party to the Nuclear Non-Proliferation Treaty.

A new U. S. policy was outlined by the president on nuclear weapon use as contained in the Nuclear Posture Review, a congressionally mandated undertaking each president does at the beginning of his tenure.

Obama said in a statement, "Today, my administration is taking a significant step ... to reduce the role of nuclear weapons in our national security strategy and focus on reducing the nuclear dangers of the 21st century, while sustaining a safe, secure and effective nuclear deterrent for the United States and our allies and partners as long as nuclear weapons exist."

Obama said that the Nuclear Posture Review recognizes nuclear terrorism presents the greatest threat to U. S. and global security.

He further said that in addition, the review recognizes that security for the United States and its allies can be increasingly defended "by America's unsurpassed conventional military capabilities and strong missile defenses."

It was said for the first time by Obama that "preventing nuclear proliferation and nuclear terrorism is now at the top of America's nuclear agenda, which affirms the central importance of the Nuclear Non-Proliferation Treaty."

The announcement comes before Obama travels to Prague -- where he first outlined his vision of non-proliferation about a year ago -- to sign a nuclear arms control treaty with Russia Thursday and ahead of next week's White House nuclear security summit.

It was further noted by Obama that to emphasize the importance of nations meeting their non-proliferation obligations, "the United States is declaring that we will not use or threaten to use nuclear weapons against non-nuclear weapons states that are party to the Nuclear Non-Proliferation Treaty and in compliance with their nuclear non-proliferation obligations."