check這個詞是廣大簽友們?nèi)〉拿?，在美國使館的官方說法是行政審理，即就是administrative processing，主要是指對一些簽證申請者的材料，進(jìn)行更近一步的審查，其所花費(fèi)的時間比一次性通過簽證審查的人所需要的時間要多。主要審查的目的，根據(jù)美國國防院的說法，主要有四點：1. 從根本上防止大殺傷性武器和導(dǎo)彈技術(shù)的擴(kuò)散；2. 限制在世界一些地區(qū)發(fā)展影響區(qū)域安全的傳統(tǒng)武器;3. 防止向恐怖主義國家輸送軍火和軍民兩用物品；4. 確保美國在某些軍事科技上的優(yōu)勢以下為節(jié)選自原文，是參考了05年的一個帖子，僅作參考：Media NoteOffice of the SpokesmanWashington, DCFebruary 11, 2005Extension of Validity for Science Related Interagency Visa ClearanceVisa applications for persons to study or work in certain sensitive scientific and technical fields are subject to an interagency clearance in Washington, DC, called Visas Mantis. Since 1998, the Visas Mantis clearance process has been used to screen against the illegal transfer of technology. Once the clearance process is complete and a visa is issued, the individual may apply for admission at a U.S. port of entry. Visas Mantis clearance and visa validity are different than the period of admission determined by a Department of Homeland Security officer at the port of entry. The U.S. Department of State, in consultation with the U.S. Department of Homeland Security, has extended the validity of Visas Mantis clearances for the F (student), J (exchange visitors), H (temporary workers), L (intracompany transferees) and B (tourist and business) categories of visas. This means that if the original visa has expired and a new visa application is filed to return to the previous study or work program in the United States, another Visas Mantis clearance may not be required. Consular officers have the discretion, if warranted, to request a Visas Mantis clearance during any visa adjudication. International students (F visas) who have received a Visas Mantis clearance and been issued a visa will benefit from having that clearance be valid for up to the length of the approved academic program, to a maximum of four years. If a student changes academic programs, the clearance will no longer be valid and a Visas Mantis review would be required should the applicant reapply for a new visa. h

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