According to my research the most weapons country is the United States currently owns 9,600 nuclear weapons, while Russia currently owns 16,800. But Russia actually always had more nuclear weapons than the United States.
Russia currently has the most, if that is what you meant by first.
From 1945 until the late 1970s or early 1980s the United States always had the most nuclear weapons. After then the USSR/Russia has had the most nuclear weapons.
Russia currently owns the biggest stockpile of nuclear weapons in the world. Also Russia made and detonated the biggest nuclear bomb in history called the Tsar bomb.
The United States currently owns 9,600 nuclear weapons, while Russia currently owns 16,800. But Russia actually always had more nuclear weapons than the United States. Russia was lacking in nuclear warheads from beginning of time to 1975. For various reasons, the USSR (and now Russia) have pretty much always had more ICBM weapons than the US, while the US maintained a larger stockpile of gravity bombs, SLBMs, and cruise missiles. Currently, as nuclear-tipped cruise missiles were forbidden under the START I treaty, only bombs, ICBMs, and SLBMs are in existence, with the number of 'usable' weapons varying over time.
America has the most nuclear weapons
Russia
As the category for this question is "Nuclear weapons", I'm presuming it refers to nuclear arms.As of 2012, the three countries with the largest stockpiles of nuclear weapons are, in order from most to least:RussiaUnited StatesFrance
In the most basic sense, proliferation of nuclear weapons is the spread of nuclear weapons and weapons usable technology in the world. In a much broader sense, it refers to the acquiring of capability to produce nuclear weapons, or weapons-grade nuclear material (high-enriched uranium, plutonium) by states previously not possessing them.
The most powerful.
nuclear weapons
RussiaUS