2.4.2 Who will be checked？

　　凡是专业涉及到高科技，可能被用来威胁美国安全的专业，签证官有权力对其进行审核。官方的敏感专业列表如下：

　　CRITICAL FIELDS LIST

　　-----------------------------

　　A. CONVENTIONAL MUNITIONS: Technologies associated with:

　　Warheads and other large caliber projectiles

　　- Reactive armor and warhead defeat systems

　　- Fusing and arming systems.

　　- Electronic countermeasures and systems

　　- New or novel explosives and formulations

　　- Automated explosive detection methods and equipment

　　B. NUCLEAR TECHNOLOGY: Technologies associated with production and use of nuclear material for both peaceful and military applications. Included are technologies for:

　　- Enrichment of fissile material

　　- Reprocessing irradiated nuclear fuel to recover produced plutonium

　　- Production of heavy water for moderator material

　　- Plutonium and tritium handling

　　Also, certain associated technologies related to nuclear physics and/or nuclear engineering. Includes materials, equipment or technology associated with:

　　- Power reactors, breeder and production reactors

　　- Fissile or special nuclear materials

　　- Uranium enrichment, including gaseous diffusion,

　　centrifuge, aerodynamic, chemical, Electromagnetic

　　Isotopic Separation (EMIS), Laser Isotope Separation (LIS)

　　- Spent fuel reprocessing, plutonium, mixed oxide nuclear

　　research

　　Inertial Confinement Fusion (ICF)

　　- Magnetic confinement fusion

　　- Laser fusion, high power lasers, plasma,

　　- Nuclear fuel fabrication including Mixed Oxide (uranium- plutonium) fuels (MOX)

　　- Heavy water production

　　- Tritium production and use

　　- Hardening technology

　　C. ROCKET SYSTEMS (including ballistic missile systems,

　　space launch vehicles and sounding rockets) and Unmanned

　　Air Vehicles (UAV) (including cruise missiles, target

　　drones, and reconnaissance drones): Technologies

　　associated with rocket systems and UAV systems. The

　　technology needed to develop a satellite launch vehicle is virtually identical to that needed to build a ballistic missile.

　　D. ROCKET SYSTEM AND UNMANNED AIR VEHICLE (UAV) SUBSYSTEMS:

　　Propulsion technologies include solid rocket motor stages, and liquid propellant engines. Other critical subsystems include re-entry vehicles, guidance sets, thrust vector

　　controls and warhead safing, arming and fusing. Many of

　　these technologies are dual-use. Technologies include:

　　- Liquid and solid rocket propulsion systems

　　- Missile propulsion and systems integration

　　- Individual rocket stages or staging/separation mechanism

　　- Aerospace thermal (such as superalloys) and high- performance structures

　　- Propulsion systems test facilities