It's the kind of justification that only a government agency could make.

After NSA insider Edward Snowden absconded with thousands of sensitive U.S. government documents from unsecured NSA servers earlier this year and gave them to the Guardian newspaper, a U.K. spy agency forced the paper to destroy hard drives containing copies of the documents because the agency said the newspaper's servers were not secure.

The U.K.'s Government Communications Headquarters, or GCHQ, claimed that Russia or China could hack into the *Guardian'*s IT network and access the documents.

Although the Guardian insisted that the documents were not stored on its network and were secure, an intelligence agency expert argued that they were still vulnerable.

To illustrate how the information was still at risk, he told editors that foreign agents could train a laser on "a plastic cup in the room where the work was being carried out ... to pick up the vibrations of what was being said" there. Vibrations on windows could similarly be monitored remotely by laser.

The bizarre explanation comes a day after the Guardian revealed that the GCHQ had forced the newspaper to destroy the documents or face legal action and a police raid.

The incident occurred July 20 in a deserted basement of the newspaper's offices. A senior editor and a Guardian computer expert used angle grinders and drills to "pulverise the hard drives and memory chips on which the encrypted files had been stored," the newspaper revealed today. They destroyed the hard drives under the watchful eye of GCHQ technicians who pointed out the critical points on circuit boards that should be targeted with the tools, and also took notes and photographs of the destruction, but left the hard drive detritus behind.

The government insisted the paper destroy the hard drives, even though they didn't contain the only copy of the documents. Reporters and editors for the paper, who are based outside of the U.K., possess copies of the documents, as do journalists working for the Washington Post and documentary filmmaker Laura Poitras, who helped Snowden connect with the two news outlets to leak the documents to them. Regardless, GCHQ officials insisted that the Guardian destroy the hard drives or surrender them.

On Sunday, the U.K. government also detained David Miranda for nine hours at Heathrow Airport under a law aimed at terrorists, some say in order to intimidate Miranda's partner, Guardian journalist Glenn Greenwald, who has published a series of stories about the spy activities of the U.S. and U.K. based on the documents provided by Snowden.

The government began pressuring the paper two weeks ago to halt its publication of stories that came out of the documents. This included stories about how the GCHQ engaged in wide-scale collection of communications from undersea cables and regularly exchanged collected data with the NSA, and about how British intelligence agencies spied on allies in London attending summits.

Government officials demanded that the paper hand over the Snowden documents on the grounds that they were stolen. The paper refused, arguing that there was a substantial public interest in the government activities revealed by the documents. The officials left unhappy but returned three weeks later following more stories published by the paper, telling editors, "You've had your fun. Now we want the stuff back."

Eventually threats of legal action and a raid grew. The paper's lawyers feared that the government might take legal action to freeze the paper's reporting on the documents – either by obtaining an injunction under a statute that covers unauthorized possession of confidential material, or by initiating criminal proceedings under the Official Secrets Act.

They viewed it as a Pyrrhic victory for the government to concede to destroying copies of the documents while still being able to retain other copies of them outside the country – particularly in the U.S. where Guardian reporters are protected by the First Amendment – and continue to publish stories about them. They chose to destroy the documents rather than hand them over to the government because they didn't want to reveal to the government everything they possessed.

"Both sides were well aware that other copies existed outside the U.K. and that the reporting on the reach of state surveillance in the 21st century would continue," the Guardian writes.