The New Strategic Arms Reduction Treaty (New START) was signed by presidents Barack Obama and Dmitry Medvedev in Prague on April 8, 2010.  The treaty requires a two-thirds majority in the Senate for ratification.  Proponents of the treaty say it enhances U.S. security by placing limits on deployed strategic warheads and by laying the groundwork for stronger international action on arms control and nonproliferation.  Critics say the limitations in the treaty on U.S. nuclear and conventional weapons undermine U.S. security and will not deter states like Iran and North Korea from seeking to acquire nuclear weapons.