Short answers, pulled from the story.
New START was signed on the 8th of April 2010 in Prague by U.S. President Barack Obama and Russian President Dmitry Medvedev. It entered into force on the 5th of February 2011, when Secretary of State Hillary Clinton and Russian Foreign Minister Sergei Lavrov exchanged instruments of ratification at the Security Conference in Munich, Germany.
New START limited each country to 1,550 deployed strategic nuclear warheads, nearly two-thirds lower than the original START treaty. The treaty also capped deployed ICBMs, submarine-launched ballistic missiles, and heavy bombers at 700, with a broader ceiling of 800 covering deployed and non-deployed launchers together.
On the 21st of February 2023, President Putin announced the suspension during an address to the Federal Assembly, citing U.S. refusal to allow inspections of NATO allies' nuclear facilities, complaints that French and British arsenals were excluded from the treaty, and allegations that the United States was developing new nuclear weapons. Russia did not formally withdraw and said it would continue to observe the numerical limits.
New START allowed each party 18 on-site inspections per year, divided into ten Type One inspections of sites with deployed systems and eight Type Two inspections covering facilities with non-deployed systems. Inspection teams could arrive with as little as 32 hours' notice.
On the 4th of February 2026, Russia's Ministry of Foreign Affairs declared the treaty's obligations no longer binding after the United States gave no formal response to Putin's September 2025 offer to extend observance by one year. The Trump administration stated that a new treaty should include China, while Russia insisted France and the United Kingdom would need to be part of any successor agreement.
The Senate voted 71-26 on the 22nd of December 2010 to ratify New START. All 56 Democratic senators, both Independent senators, and 13 Republicans voted in favor. President Obama completed the American ratification process on the 2nd of February 2011.