Preface: The Bush and Obama administrations both claimed that spying on Americans was justified by 9/11. Specifically, they said that they could have caught one of the 9/11 hijackers living in San Diego if they could have spied on phone calls on American soil.

However - as demonstrated below - that claim is totally false.

ProPublica notes:

In defending the NSA’s sweeping collection of Americans’ phone call records, Obama administration officials have repeatedly pointed out how it could have helped thwart the 9/11 attacks: If only the surveillance program been in place before Sept. 11, 2001, U.S. authorities would have been able to identify one of the future hijackers who was living in San Diego [named Khalid al Mihdhar]. Last weekend, former Vice President Dick Cheney invoked the same argument.

*** Indeed, the Obama administration’s invocation of the Mihdhar case echoes a nearly identical argument made by the Bush administration eight years ago when it defended the NSA’s warrantless wiretapping program.

The reality is different.

Initially, an FBI informant hosted and rented a room to Mihdhar and another 9/11 hijacker in 2000.

Investigators for the Congressional Joint Inquiry discovered that an FBI informant had hosted and even rented a room to two hijackers in 2000 and that, when the Inquiry sought to interview the informant, the FBI refused outright, and then hid him in an unknown location, and that a high-level FBI official stated these blocking maneuvers were undertaken under orders from the White House.

As the New York Times notes:

Senator Bob Graham, the Florida Democrat who is a former chairman of the Senate Intelligence Committee, accused the White House on Tuesday of covering up evidence ….The accusation stems from the Federal Bureau of Investigation’s refusal to allow investigators for a Congressional inquiry and the independent Sept. 11 commission to interview an informant, Abdussattar Shaikh, who had been the landlord in San Diego of two Sept. 11 hijackers.

So mass surveillance of Americans isn't necessary, when the FBI informant should have apprehended the hijackers.

Moreover, the NSA actually did intercept Mihdhar's phone calls before 9/11.

We reported in 2008:

We’ve previously pointed out that the U.S. government heard the 9/11 plans from the hijackers’ own mouth. Most of what we wrote about involved the NSA and other intelligence services tapping top Al Qaeda operatives’ phone calls outside the U.S. However, as leading NSA expert James Bamford - the Washington Investigative Producer for ABC’s World News Tonight with Peter Jennings for almost a decade, winner of a number of journalism awards for coverage national security issues, whose articles have appeared in dozens of publications, including cover stories for the New York Times Magazine, Washington Post Magazine, and the Los Angeles Times Magazine, and the only author to write any books (he wrote 3) on the NSA – reports, the NSA was also tapping the hijackers’ phone calls inside the U.S. Specifically, hijackers Khalid al-Mihdhar and Nawaf al-Hazmi lived in San Diego, California, for 2 years before 9/11. Numerous phone calls between al-Mihdhar and Nawaf al-Hazmi in San Diego and a high-level Al Qaeda operations base in Yemen were made in those 2 years. The NSA had been tapping and eavesdropping on all calls made from that Yemen phone for years. So NSA recorded all of these phone calls. Indeed, the CIA knew as far back as 1999 that al-Mihdhar was coming to the U.S. Specifically, in 1999, CIA operatives tailing al-Mihdhar in Kuala Lumpur, Malaysia, obtained a copy of his passport. It contained visas for both Malaysia and the U.S., so they knew it was likely he would go from Kuala Lumpur to America.

We asked top NSA whistleblower William Binney – a highly-credible 32-year NSA veteran with the title of senior technical director, who headed the agency’s digital data gathering program (featured in a New York Times documentary, and the source for much of what we know about NSA spying) – what he thought of the government's claim that mass surveillance of Americans would have caught Mihdhar and prevented 9/11.

Binney responded:

Of course they could have and did have data on hijackers before 9/11. And, Prism did not start until 2007. But they could get the data from the "Upstream" collection. This is the Mark Klein documentation of Narus equipment in the NSA room in San Francisco and probably other places in the lower 48. They did not need Prism to discover that. Prism only suplemented the "Upstream" material starting in 2007 according to the slide.

Details here and here.

Indeed, widespread spying on Americans began before 9/11 (confirmed here, here, here and here.

And U.S. and allied intelligence heard the 9/11 hijackers plans from their own mouths:

According to journalist Christopher Ketcham, America’s close ally Israel tracked the hijackers’ every move prior to the attacks, and sent agents to film the attack on the World Trade Centers

The National Security Agency and the FBI were each independently listening in on the phone calls between the supposed mastermind of the attacks and the lead hijacker. Indeed, the FBI built its own antenna in Madagascar specifically to listen in on the mastermind’s phone calls

According to various sources, on the day before 9/11, the mastermind told the lead hijacker “tomorrow is zero hour” and gave final approval for the attacks. The NSA intercepted the message that day and the FBI was likely also monitoring the mastermind’s phone calls

The CIA and the NSA had been intercepting phone calls by the hijackers for years (see also this)

According to the Sunday Herald, two days before 9/11, Bin Laden called his stepmother and told her “In two days, you’re going to hear big news and you’re not going to hear from me for a while.” U.S. officials later told CNN that “in recent years they’ve been able to monitor some of bin Laden’s telephone communications with his [step]mother. Bin Laden at the time was using a satellite telephone, and the signals were intercepted and sometimes recorded.” Indeed, before 9/11, to impress important visitors, NSA analysts would occasionally play audio tapes of bin Laden talking to his stepmother.

And according to CBS News, at 9:53 a.m on 9/11, just 15 minutes after the hijacked plane had hit the Pentagon, “the National Security Agency, which monitors communications worldwide, intercepted a phone call from one of Osama bin Laden’s operatives in Afghanistan to a phone number in the former Soviet Republic of Georgia”, and secretary of Defense Rumsfeld learned about the intercepted phone call in real-time (if the NSA monitored and transcribed phone calls in real-time on 9/11, that implies that it did so in the months leading up to 9/11 as well)

But even with all of that spying, the government didn’t stop the hijackers … even though 9/11 was entirely foreseeable.

ProPublica notes:

“There were plenty of opportunities without having to rely on this metadata system for the FBI and intelligence agencies to have located Mihdhar,” says former Senator Bob Graham, the Florida Democrat who extensively investigated 9/11 as chairman of the Senate’s intelligence committee. These missed opportunities are described in detail in the joint congressional report produced by Graham and his colleagues as well as in the 9/11 Commission report. *** Mihdhar was on the intelligence community’s radar at least as early as 1999. That’s when the NSA had picked up communications from a “terrorist facility” in the Mideast suggesting that members of an “operational cadre” were planning to travel to Kuala Lumpur in January 2000, according to the commission report. The NSA picked up the first names of the members, including a “Khalid.” The CIA identified him as Khalid al Mihdhar. The U.S. got photos of those attending the January 2000 meeting in Malaysia, including of Mihdhar, and the CIA also learned that his passport had a visa for travel to the U.S. *** Using their true names, Mihdhar and Hazmi for a time beginning in May 2000 even lived with an active FBI informant in San Diego. *** Let’s turn to the comments of FBI Director Robert Mueller before the House Judiciary Committee last week. Mueller noted that intelligence agencies lost track of Mihdhar following the January 2000 Kuala Lumpur meeting but at the same time had identified an “Al Qaida safe house in Yemen.” He continued: “They understood that that Al Qaida safe house had a telephone number but they could not know who was calling into that particular safe house. We came to find out afterwards that the person who had called into that safe house was al Mihdhar, who was in the United States in San Diego. If we had had this [metadata] program in place at the time we would have been able to identify that particular telephone number in San Diego.” In turn, the number would have led to Mihdhar and potentially disrupted the plot, Mueller argued. (Media accounts indicate that the “safe house” was actually the home of Mihdhar’s father-in-law, himself a longtime al Qaida figure, and that the NSA had been intercepting calls to the home for several years.) The congressional 9/11 report sheds some further light on this episode, though in highly redacted form. The NSA had in early 2000 analyzed communications between a person named “Khaled” and “a suspected terrorist facility in the Middle East,” according to this account. But, crucially, the intelligence community “did not determine the location from which they had been made.” In other words, the report suggests, the NSA actually picked up the content of the communications between Mihdhar and the “Yemen safe house” but was not able to figure out who was calling or even the phone number he was calling from. *** Theories about the metadata program aside, it’s not clear why the NSA couldn’t or didn’t track the originating number of calls to Yemen it was already listening to. Intelligence historian Matthew Aid, who wrote the 2009 NSA history Secret Sentry, says that the agency would have had both the technical ability and legal authority to determine the San Diego number that Mihdhar was calling from. “Back in 2001 NSA was routinely tracking the identity of both sides of a telephone call,” [9/11 Commission Executive Director Philip Zelikow] told ProPublica. *** There's another wrinkle in the Mihdhar case: In the years after 9/11, media reports also suggested that there were multiple calls that went in the other direction: from the house in Yemen to Mihdhar in San Diego. But the NSA apparently also failed to track where those calls were going. In 2005, the Los Angeles Times quoted unnamed officials saying the NSA had well-established legal authority before 9/11 to track calls made from the Yemen number to the U.S. In that more targeted scenario, a metadata program vacumming the phone records of all Americans would appear to be unnecessary.

In other words, the NSA had the technical ability and legal authority to intercept calls between Midhar and Yemen before 9/11 ... and it actually did so.

In addition,Wikipedia notes:

Mihdhar was placed on a CIA watchlist on August 21, 2001, and a note was sent on August 23 to the Department of State and the Immigration and Naturalization Service (INS) suggesting that Mihdhar and Hazmi be added to their watchlists. *** On August 23, the CIA informed the FBI that Mihdhar had obtained a U.S. visa in Jeddah. The FBI headquarters received a copy of the Visa Express application from the Jeddah embassy on August 24, showing the New York Marriott as Mihdhar's destination. On August 28, the FBI New York field office requested that a criminal case be opened to determine whether Mihdhar was still in the United States, but the request was refused. The FBI ended up treating Mihdhar as an intelligence case, which meant that the FBI's criminal investigators could not work on the case, due to the barrier separating intelligence and criminal case operations. An agent in the New York office sent an e-mail to FBI headquarters saying, "Whatever has happened to this, someday someone will die, and the public will not understand why we were not more effective and throwing every resource we had at certain 'problems.'" The reply from headquarters was, "we [at headquarters] are all frustrated with this issue ... [t]hese are the rules. NSLU does not make them up." The FBI contacted Marriott on August 30, requesting that they check guest records, and on September 5, they reported that no Marriott hotels had any record of Mihdhar checking in. The day before the attacks, the New York office requested that the Los Angeles FBI office check all local Sheraton Hotels, as well as Lufthansa and United Airlines bookings, because those were the two airlines Mihdhar had used to enter the country. Neither the Treasury Department's Financial Crimes Enforcement Network nor the FBI's Financial Review Group, which have access to credit card and other private financial records, were notified about Mihdhar prior to September 11. *** Army Lt. Col. Anthony Shaffer and Congressman Curt Weldon alleged in 2005 that the Defense Department data mining project Able Danger identified Mihdhar and 3 other 9/11 hijackers as members of an al-Qaeda cell in early 2000.

Similarly, even though the alleged Boston bombers' phones were tapped - and NBC News reports, "under the post-9/11 Patriot Act, the government has been collecting records on every phone call made in the U.S." - mass surveillance did not stop the other terror attack on U.S. soil since 9/11.

In reality - despite the government continually grasping at straws to justify its massive spying program - top security experts say that mass surveillance of Americans does not keep us safe. Indeed, experts say that mass surveillance interferes with catching bad guys.