Alpha, fallout, UV, a small number of obsolete chemical weapons.
alpha or beta radiation
Mostly inhalation/ingestion of alpha emitter dust particles. These offer little protection from other types of radiation sources.
alpha
Protective clothing and masks can help shield against alpha and beta radiation exposure, as well as some forms of nuclear fallout particles. However, they are less effective against more penetrating gamma radiation and neutron radiation, which require specialized shielding and thicker barriers for protection.
to protect yourself and threaten other countries
Nuclear weapons emit various types of radiation, including gamma radiation, neutron radiation, and thermal radiation. These forms of radiation can have harmful effects on living organisms and the environment.
Their clothing.
That is a difficult question to answer. You cannot protect yourself from the blast, flash, thermal burns, or prompt radiation except by being nowhere near it when it goes off. You cannot protect yourself from the firestorm after the blast, even in some kind of shelter because the firestorm will suck all the oxygen out of the shelter. You can protect yourself from fallout after the fact if you can get to a properly built and adequately supplied fallout shelter before significant fallout has fallen. You will then have to live in the fallout shelter from about 1 to 5 months, never leaving it until an outside radiation survey by a qualified person with a calibrated meter indicates the levels are again safe. Once you leave all food and water sources will have to be tested for contamination before use, also frequent radiation surveys will have to be done to be sure you don't move into a "hot spot". Read Dean Ing's book "Pulling Through".
Because when you have achieved something that other countries want you need to protect yourself. The main goal of the military is not to "take over" but to protect the assets and interests of a nation.
energy/electricity/weapons
Biological weapons can cause infectious diseases. The radiation from nuclear weapons can cause either short term, but often fatal, radiation sickness or in the long term cancer.
to protect them selfs