Munich (Agencies): US Secretary of State Hillary Clinton launched an important nuclear arms reduction pact with Russia on Saturday, a showpiece of Washington's "reset" of ties with its former Cold War adversary.

The new START nuclear arms reduction treaty officially came into force when Clinton and her Russian counterpart Sergei Lavrov exchanged ratification documents at a security
conference here.

"Today we exchange the instruments of ratification for a treaty that lessens the nuclear danger facing the Russian and American people and the world," Clinton said.

The chief US diplomat hailed the agreement as another example of "clear-eyed" cooperation between the two military powers, "part of a journey we have been taking for more than 60
years."

The pact cuts back existing warhead ceilings by 30 percent over the next 10 years and limits each side to 700 deployed long-range missiles and heavy bombers.

The original 1991 pact expired at the end of 2009 amid sharp differences over how the two sides planned to proceed.