After extended wrangling among lawmakers in both countries, the new START treaty between the U.S. and Russia went into effect Saturday at the global security conference in Munich.

"The principles of equality, parity, equal and undivided security lay a solid foundation for the modern Russian-American cooperation in various spheres," Russian Foreign Minister Sergei Lavrov, appearing with Secretary of State Hillary Rodham Clinton to exchange the treaty documents, said, according to RIA Novosti.

The last START treaty expired in December 2009. President Obama and Russian President Dmitry Medvedev signed a new treaty in Prague last April, but ratification became hung up in the Senate over concerns about modernization of the nuclear arsenal and resistance to Obama trying to push the treaty, expanded from its original form, through in the lame-duck session.

After Obama won the 11th-hour approval for the nuclear-arms pact, Russian lawmakers became concerned with amendments that U.S. senators had attached to the treaty, and delayed it for a short time around the holidays.

The treaty cuts Russian and U.S. nuclear warhead stockpiles from a maximum of 2,200 in the 2002 treaty to 1,550. Together, the two countries hold 95 percent of the world's nuclear weapons.

Within weeks, the countries are expected to send inspectors to keep tabs on each other's nuclear arsenals.

"Two years ago we all laughed about the translation of the ceremonial 'reset' button I gave to the Foreign Minister," Clinton said. "But when it came to the translation that mattered most, we turned words into action to reach a milestone in our strategic partnership."