The bombing at Domodedovo Airport was another link in the mysterious chain of terrorist attacks in Russia — mysterious because the terrorists rarely claim responsibility or make demands. This isn’t a unique situation. The same thing occurs in Israel and Iraq, although their civil wars have been simmering for so long that everyone knows the usual suspects and their reasons. But in Russia, terrorist attacks often leave everyone guessing who was responsible and what their goal is.

Because it is Russia, every terrorist attack is immediately followed by a number of theories of who was responsible, which are hotly debated on the Internet. The first version about the organizers of the Domodedovo incident was Chechen rebels. Despite a lack of evidence, this version quickly became the most popular — in fact, so popular that Prime Minister Vladimir Putin had to deny it personally. “According to preliminary information, this terrorist act has no relation to the Chechen Republic,” Putin said.

A more likely version is that the bombing was done by terrorists from another republic in the North Caucasus, such as Dagestan or Kabardino-Balkaria, who figure more frequently than Chechens as organizers of terrorist attacks in Moscow. Investigators have already reported that they have identified the suicide bomber as a 20-year-old man from the North Caucasus.

Yet another version lays the blame for the airport bombing on an international terrorist organization. Lifenews.ru published a copy of an Interior Ministry document, which may or may not be authentic, stating that in December a group of terrorists arrived in Moscow after training in Pakistan. The document noted that they rented an apartment in southern Moscow where they could make explosives. But since these Pakistan-trained terrorists originally came from the North Caucasus, this version also points to a trail leading south.

When Moskovsky Komsomolets surveyed its readers on Jan. 27, 41 percent of Muscovites responded that the terrorist attack at Domodedovo was most likely organized by the country’s own siloviki. This response was so embarrassing that the next day the newspaper felt compelled to issue a clarification. Apparently, the respondents hadn’t meant currently employed siloviki; they meant retired or former siloviki. But as the blogger Agitator-mass wrote, “We can accept that the newspaper meant that, but who knows what readers had in mind?”

Russia always produces a huge crop of wild conspiracy theories, but in the case of terrorist attacks, there is some justification. No one has definitively disproved the theory put forth by former Federal Security Service agent Alexander Litvinenko in his book “Blowing Up Russia” that the apartment building bombings in 1999 were carried out by the FSB. But the restrained and appropriate response by the country’s leaders after the tragedy at Domodedovo makes an FSB bombing unlikely.

At the World Economic Forum in Davos, President Dmitry Medvedev voiced perhaps the most extravagant version. He said terrorists’ goal was to foil his appearance at the forum. It’s hard to say why the president considered his mostly ceremonial presence to be so crucial, since Russia was well represented by other senior officials. As the blogger Irvell39 commented sarcastically, “Without him, the economy would collapse, the forum would fall apart, and the sun would leave its orbit.” It’s also hard to imagine that terrorists follow international events as carefully as anti-globalists.

There are plenty of other versions. The attack was organized by the Russian nationalist underground in Moscow. (The explosion occurred right after a flight arrived from Tajikistan.) Or by somebody wanting to disrupt the plans of East Line Group, which operates Domodedovo, to issue an initial public offering. Or even “the Israeli lobby.”

But as opposition leader Boris Nemtsov — aka B_nemtsov — wrote: “Over the last 11 years in Russia, the number of terrorist attacks has risen dramatically. From 2000 to 2009, they have increased more than sixfold and reached the astronomical figure of more than 750 incidents a year. This is obviously a total failure of the country’s anti-terrorism program.”

Unfortunately, the terrorist act at Domodedovo confirms Nemtsov’s words.