The Boston Marathon bombings last week, which killed three and wounded over 170, were seized on to implement a far-reaching attack on democratic rights, including a police lockdown of an entire city. As with previous incidents, much remains unknown, including the motive of those who allegedly carried it out, whether others were involved, and what connection the FBI and other government agencies had to them.

In a televised statement immediately after the capture of 19-year-old Dzhokhar Tsarnaev, the surviving suspect in the bombings, President Barack Obama told the American public: “Obviously, tonight there are still many unanswered questions. Among them, why did young men who grew up and studied here, as part of our communities and our country, resort to such violence? How did they plan and carry out these attacks, and did they receive any help?”

However, it is the government that has released very little information about what it knows. Moreover, the Obama administration has decreed that Dzhokhar will be denied his Miranda rights, allowing CIA, FBI and military interrogators to question him without the presence of an attorney, thereby further limiting any information surfacing outside of what is vetted by the government and its intelligence agencies.

In addition to the questions raised by Obama, there are a number of others that bear serious scrutiny.

• How did the two brothers obtain the explosives used in the bombings?
• What relationship existed between the Tsarnaev brothers and the FBI and other US intelligence agencies?
• Did US authorities have any knowledge about the Boston bombing plot before it was executed?
• What role did US policy in relation to Russia and the separatist movements in Chechnya and other parts of the North Caucasus play in the US government’s attitude toward the Tsarnaevs?

While much remains murky about these and other issues, one thing is clear: the Boston bombing, like virtually every other major terrorist incident, real or invented, since the September 11, 2001 attacks on New York City and Washington, was carried out by someone who was known to and under surveillance by US intelligence agencies.

There have been increasing questions raised concerning the FBI’s handling of a request from a foreign government, presumed to be Russia, that it investigate Tamerlan Tsarnaev on suspicion of involvement in Islamist terrorism.

The request came in advance of a six-month visit that Tamerlan made to Russia beginning in January of last year, during which he stayed with his father in Dagestan and visited Chechnya, where several members of the family live.

In a statement released in the wake of the Boston bombings, the FBI acknowledged that Russian authorities had determined that Tamerlan Tsarnaev was a “follower of radical Islam and a strong believer, and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country’s region to join unspecified underground groups.”

The FBI said that in response to this request it “checked US government databases and other information to look for such things as derogatory telephone communications, possible use of online sites associated with the promotion of radical activity, associations with other persons of interest, travel history and plans, and education history.”

The statement concluded that the FBI “did not find any terrorism activity, domestic or foreign, and those results were provided to the foreign government in the summer of 2011.”

The Russian media has reported that Russian security services again contacted the FBI about Tamerlan Tsarnaev in November of last year.

Both of the parents of the two suspects have provided accounts of the FBI’s role that contradict the agency’s public statement.

The mother of the two brothers, Zubeidat Tsarnaeva, a naturalized US citizen, told Russia Today that the FBI agents had told her that “Tamerlan was an extremist leader and they were afraid of him. They told me whatever information he is getting, he gets from these extremists’ web sites.”

“It is a setup,” she added. “He was controlled by FBI for three to five years. They knew what my son was doing. They knew what actions and what sites on the Internet he was going… So how could this happen? How could they, they were controlling his every step, and they are telling today that this is a terrorist act.”

In an interview with the Reuters news agency, the young men’s father, Anzor Tsarnaev, said that the FBI had visited the family’s home in Cambridge, Massachusetts at least five times looking for Tamerlan. He said: “They said there were doing preventive work. They were afraid there might be some explosions on the streets of Boston.”

The father said that he had been present at one FBI interrogation in which agents had told his son, “We know what sites you are on, we know where you are calling, we know everything about you. Everything.” Like the mother, he insisted that his sons had been “framed up.”

Russian sources reported that both parents had subsequently been questioned by Russia’s Federal Security Service, after which they cut off further contact with the Western media.

Reports of FBI involvement with Tamerlan Tsarnaev have led to criticism by US lawmakers, including South Carolina Republican Senator Lindsey Graham, who has called for the younger brother to be treated as an “enemy combatant” and turned over to the US military. He said in a Sunday television interview that “the ball was dropped” by the FBI.

There have been no explanations forthcoming about how “the ball was dropped.” And without either of the two suspects or anyone else providing a motive for the bombings, much is unclear.

Among the explanations that have been suggested is one from the Israeli web site Debka, citing “counterterrorism and intelligence sources,” who it said had concluded that the two brothers were “recruited by US intelligence as penetration agents” to gain access to jihadist networks in the Russian Caucasus, but then “turned coat and bit their recruiters.”

It has been widely charged that Washington has offered covert support to Chechen and other Islamist separatists in the Caucasus, who have waged two wars with Russian forces in 1994-1996 and again in 1999.

Chechen fighters have also been reportedly active in the Western-backed Islamist militias fighting to overthrow the regime of Bashar al-Assad in Syria. Videos supporting this war for regime-change were found on Tamerlan Tsarnaev’s YouTube channel, along with other Islamist material. The channel had some 700 subscribers. Moscow Times quoted Russian “intelligence expert” Andrei Soldatov as questioning the FBI’s handling of the case. “He was very open about his beliefs,” he said of Tamerlan. “I’m at a loss as to why the FBI didn’t pay attention to him then.”

A web site backing the Islamist groups in the North Caucasus posted a statement on Sunday denying any link between them and those who carried out the Boston Marathon bombings. “The Caucasus fighters are not waging any military activities against the United States of America,” the Kavkazcenter.com web site said. Servers for the site are located in the US.

A Russian intelligence source also told AFP, “At the moment we have no credible information about the Tsarnaev brothers’ involvement with the Caucasus Emirate movement,” the main Islamist organization in the region. The group has previously claimed responsibility for terrorist attacks such as the bombing of the Moscow airport in January 2011 in which 37 died and bombings of its metro system in 2010, which killed over 40.

As to whether the government had prior knowledge of the Boston bombing plot before last Monday’s explosions at the Marathon finish line, participants in the event have cited what they saw at the time as unusual developments. The coach of the University of Mobile’s cross-country team, Ali Stevenson, told the Alabama media that he found it odd that bomb-sniffing dogs were brought out at both the starting and finish lines.

“They kept making announcements to the participants do not worry, it’s just a training exercise,” he said. He added that he had also observed “law enforcement spotters” on roofs at the start of the race. “Evidently, I don’t believe they were just having a training exercise,” Stevenson said. “I think they must have had some sort of threat or suspicion called in.”

If such prior knowledge did exist, this raises another question. In all but a handful of cases, every major terrorist plot reported in the US over the past decade has been the product of a sting operation organized by the FBI or other police agencies. In almost all of these cases, those arrested and prosecuted for terrorism would never have had the means or even the intention of carrying out such acts without the guiding hand of covert informers and agent provocateurs.

This pattern goes back at least to the 1993 bombing of the World Trade Center, in which a former Egyptian army officer, Emad Salem acting as a paid FBI informant, actually participated in building the bomb, claiming that the original plan had been to substitute harmless powder for the explosives.

Were the Boston bombings the result of such an operation that got out of control? Or did sections of the state know about it and allow it to go forward?

How the Boston Marathon bombing plot unfolded and what motives lay behind it are still not known. Only one thing is certain: whatever the source of this terrorist atrocity, it will be used by the US government as a pretext to escalate militarism abroad and repression at home.