由于害怕机场、发电厂以及军事基地等成为恐怖袭击的目标，美国政府在9·11袭击后关闭了大量联邦网站，然而一项调查却表明，这一举动对于毫无用处，因为相似或更详尽的信息完全可以通过其他渠道获得。

　　进行调查的兰德公司指出，只有对其中4个网站的访问限制有可能会加固国土安全，而这一数字仅占被关闭数据库总数的1%。这四个网站中包括两个石油管道，一个核反应堆网站以及一个大坝网站。该公司要求政府官员考虑重新开放以国家安全的名义关闭的30多个网站。

　　调查报告的主要撰写者约翰·贝克（John Baker）说：“应该是好好检讨政府当时的选择是否正确的时候了。”赞成政府事务公开的人士认为，9·11恐怖袭击后布什政府关闭许多政府网站的做法过于草率。美国科学家联盟的主席斯蒂夫-阿弗特古德（Steven Aftergood）说：“这样做简直是大错特错。我希望这个调查就够让政府重新变得理智一些。到目前为止他们做出的决定都太草率了。”

　　上述为期一年的调查表明，没有任何联邦网站提供的信息是恐怖分子不可缺少的，也就是说，没有这些信息一样可以进行恐怖袭击。

　　调查者建议官员们评估包含有用信息的66个联邦网站，但并不赞成限制访问，因为类似或更详尽的信息完全可以通过其他渠道获得。他们指出，有629个联邦网站的信息可以从因特网其他网址访问，这些网址包括某些“最敏感地点”的重要数据。

　　Federal officials should consider reopening public access to about three dozen Web sites withdrawn from the Internet after the Sept. 11, 2001, attacks, a government-financed study says, because the sites pose little or no risk to homeland security.

　　The Rand Corp. said the overwhelming majority of federal Web sites that reveal information about airports, power plants, military bases and other potential terrorist targets need not be censored because similar or better information is easily available elsewhere.

　　Rand identified four Web pages that might merit the restrictions imposed after the attacks.

　　"It's a good time to take a closer look at the choices that they made at the time," said John Baker, principal author of the study, which was funded by the National Geospatial-Intelligence Agency, the government's intelligence mapping agency.

　　Advocates of open government said the report shows the Bush administration acted rashly after the suicide attacks when it scrubbed numerous government Web sites.

　　"It was a gigantic mistake, and I hope the study brings some rationality back to this policy," said Steven Aftergood, director of the Federation of American Scientists' project on government secrecy. "Up to now, decisions have been made on a knee-jerk basis."

　　Rand's National Defense Research Institute identified 629 Internet-accessible federal databases that contain critical data about specific locations. Co-author Beth Lachman said they "appeared to be the most sensitive sites" among 5,000 federal Web pages the researchers checked.

　　The study, conducted between mid-2002 and mid-2003, found no federal Web sites that contained target information essential to a terrorist - in other words, information a terrorist would need to launch an attack.

　　It identified four databases - less than 1 percent of the 629 - where restricting access probably would enhance homeland security. None was available to the general public anymore. Those sites included two devoted to pipelines, one to nuclear reactors and one to dams.

　　Researchers recommended that officials evaluate 66 databases with some useful information, but they didn't anticipate restrictions would be needed because similar or better data probably could be easily obtained elsewhere.

　　The remaining 559 databases "are probably not significant for addressing attackers' information needs and do not warrant any type of public restriction," the report said. It said that any information they contain that could be useful to terrorists is easily obtained elsewhere, often by simple, legal observation in an open society.

　　The Rand researchers found that 30 federal agencies or departments make public, on paper or online, "geospatial information" about critical or symbolic locations and structures. That kind of data can be as simple as a telephone book or as complex as an Internet database that discloses how many people live near each of the nation's power plants or toxic chemical storage sites.

　　After Sept. 11, federal agencies scrambled to pull such data off the Internet. The Transportation Department removed pipeline maps. The Environmental Protection Agency deleted descriptions of risk management plans for chemicals stored at 15,000 sites. The Nuclear Regulatory Commission took down its Web site, although much of it is now back online.

　　Using Internet archives that preserve old Web pages or detailed written descriptions, researchers identified 39 federal geospatial databases taken off-line since Sept. 11.

　　Other than the four databases that posed some risk, "these restrictions need to be more thoroughly assessed," the researchers wrote.

　　"Under the circumstances, these officials took prudent steps but in a very piecemeal, patchwork way," Baker said.

　　The study proposed a framework for analyzing and possibly restoring such data to the Internet:

　　How useful would it be to an attacker? Far more detailed information is needed to plan an attack than to pick a target, but most federal Web sites are too general to help with more than target selection.

　　Is similar or better data readily available elsewhere? If so, "the net security benefits of restricting access ... may be minimal or nonexistent" and could "possibly lead ... to a false sense of security at worst."

　　Does the gain in security from restrictions outweigh any harm to those using the data, such as police and fire departments, economic planners or private companies?

　　For instance, Rand advocated that an Environmental Protection Agency Web site that discloses where toxic chemicals are stored and in what quantity should not be restricted because its value to terrorists is outweighed by its value to communities preparing for emergencies.

　　Restricting the site would "diminish the public good that comes from providing local communities access to information that can significantly affect the well-being of citizens," the study said.

　　To demonstrate the futility of removing government data that isn't unique, Rand researchers picked out 300 non-federal Web sites that had similar or better information about critical U.S. targets than federal pages.

　　For instance, an online scuba magazine contains a divers' description of the ocean depths and currents around an oil-drilling platform off the southern California coast that would be more useful to terrorists than the federal sites that described the platform.