Yes s/he can. The President is at the top of the National Command Authority which controls the release and execution of Nuclear Control Orders.
The United States has a two-man rule in place. Only the president can order the release of nuclear weapons but the order must be confirmed by the Secretary of Defense.
USUSSRUKFranceChinaetc.
In the US, yes he has the "football" that cryptographically controls the PALs (Permissive Action Link) that arms and disarms each device. Elsewhere nobody knows for sure.
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
Nuclear weapons are typically launched through a highly secure and controlled process involving multiple layers of authentication and authorization to prevent unauthorized use. In the United States, for example, the President can order a nuclear strike using the "nuclear football," a briefcase containing communication tools and codes. The order is confirmed through a series of checks with military officials, and then transmitted to missile launch facilities or submarines equipped with nuclear missiles. Once the launch codes are verified, the weapons are activated and launched toward their targets.
How can it be nuclear and biological at the same time.
Nations that are known or believed to possess nuclear weapons are sometimes referred to as the nuclear club. In order of acquisition of nuclear weapons these are: the United States, Russia, the United Kingdom, France, and China.
Mutually assured destruction, called for short (and sensibly so): the M.A.D. Principle.
It's a pact in order to reduce the production of nuclear weapons
I feel uneasy about your plan to start a mail order nuclear weapons business.
No, this would require legislation from Congress. This is because currently there is no law banning assault weapons for an executive order to clarify the scope of.
The peak was on the order of 10,000 having a very wide range of yields.