世界各國製造核武器需要多長時間，日本真的可以7天造出核武器嗎？！

核武器（英文名：nuclear weapon）是利用能自持進行的原子核裂變或核聚變反應瞬時釋放的巨大的能量，產生爆炸作用，並具有大規模毀傷破壞效應的武器。主要包括裂變武器（第一代核武器，通常稱為原子彈）和聚變武器（亦稱為氫彈，分為兩級及三級式）。核武器也叫核子武器或原子武器。從廣義上說核武器是指包括投擲或發射系統在內的具有作戰能力的核武器系統。核武器通常指狹義的核武器，即由核戰鬥部與製導，突防等裝置裝入彈頭殼體組成的核彈。核戰鬥部的主體是核爆炸裝置，簡稱核裝置。核裝置與引爆控制系統等一起組成核戰鬥部。將核戰鬥部與製導、突防等裝置裝入彈頭殼體，即構成彈道導彈的核彈頭。廣義的核武器通常指由核彈、投擲/發射系統和指揮控制、通信和作戰支持系統等組成的、具有作戰能力的核武器系統。
A nuclear weapon (English name: nuclear weapon) is a weapon that uses the huge energy released instantaneously by a self-sustaining nuclear fission or nuclear fusion reaction to produce an explosive effect and has a large-scale damage effect. It mainly includes fission weapons (the first generation of nuclear weapons, usually called atomic bombs) and fusion weapons (also called hydrogen bombs, which are divided into two-stage and three-stage types). Nuclear weapons are also called nuclear weapons or atomic weapons. Broadly speaking, nuclear weapons refer to combat-capable nuclear weapons systems, including drop or launch systems. Nuclear weapons usually refer to nuclear weapons in a narrow sense, that is, nuclear bombs composed of nuclear warheads and guidance, penetration and other devices into the warhead casing. The main body of a nuclear warhead is a nuclear explosive device, referred to as a nuclear device. The nuclear device and the detonation control system together form the nuclear warhead. The nuclear warhead and guidance, penetration and other devices are put into the warhead shell, which constitutes the nuclear warhead of the ballistic missile. In a broad sense, nuclear weapons usually refer to a nuclear weapon system with combat capability, which consists of nuclear bombs, throwing/launching systems, command and control, communication and combat support systems.