Mass transportation system has already been a very important public traffic facility in the developed countries.

轨道交通在发达国家已经成为非常重要的公共交通工具。

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As outlined in that report, the most severe threat facing any transportation system is a weapon of mass destruction such as a nuclear device or a biological weapon.

正如报告所概括的，所有交通系统面临的最严重威胁，是大规模毁灭性武器，例如核设备或生物武器。

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In particular, Japan's limited useful land mass makes such a system an imperative for its transportation needs in the 1990s and beyond.

CENTERFORSECURITYPOLICY: Center For Security Policy