START II, or the Strategic Arms Reduction Treaty II, was a bilateral agreement between the United States and Russia aimed at reducing the number of strategic nuclear weapons. Signed in 1993, it built upon the earlier START I treaty and sought to limit the number of deployed warheads to 3,000-3,500 for each country by the year 2007. Although START II was signed, it never entered into force due to various geopolitical factors, including the U.S. withdrawal from the ABM Treaty in 2002. The treaty's failure highlighted the challenges of arms control in a changing global landscape.