START is the nuclear arms reduction treaty between the US and the Russian Federation. Limiting the amount of strategic warheads each country are allowed to posses, the mark currently set at a max of 1,550 nuclear warheads.
In addition to the limit of nuclear arms, the treaty requires each side to share biannual data exchanges with breakdowns of all nuclear delivery vehicles/launchers, their whereabouts, everything. Complete transparency about all production, movement, testing, etc. Anything and everything Russia and the US do with nuclear warheads, they are supposed to tell each other about.
The treaty allows for up to 18 on-site inspections per year for US and Russian inspection teams. Which Russia have now expressed they are suspending. Today the Russian Ministry of Foreign Affairs stated that they have been forced to:
"resort to this measure as a result of Washington's insistence that it will inevitably seek to restart inspection activities on conditions that do not take current realities into account."I am still looking, but cannot find exactly what The Russia MFA are referring to when they say "current realities", but I'm sure the allegations of US biological weapons production and the Special Military Operation in Ukraine are contributing factors.
Comment: More on the inauguration:
And over in Costa Rica: