START I is a strategic arms reduction treaty between the United States and Russia, aimed at limiting the number of nuclear weapons each country possesses. Signed in 2010, it builds on previous agreements and focuses on reducing deployed strategic warheads and delivery systems. The treaty emphasizes verification measures to ensure compliance and promote transparency between the two nations. The agreement allows for a total of 1,550 deployed strategic warheads per country, along with limits on the number of delivery vehicles, such as intercontinental ballistic missiles and bombers. START I plays a crucial role in global nuclear disarmament efforts and enhances international security.