MOSCOW -- Russian security officials released new details Tuesday about a group suspected of planning a terror attack in Moscow with support from the Islamic State group, saying it was comprised of 12 Russian citizens, including at least one who had been trained in Syria.
Only three suspects have been identified so far and all are men in their 20s from Chechnya, a predominantly Muslim region in southern Russia where an Islamic insurgency still simmers after two separatist wars. They appeared Tuesday in a Moscow court, which ordered them held for two months.
Security officials previously had not said how many suspects were arrested following Sunday's raid of a Moscow apartment where explosives were found. They said the suspects planned an attack on Moscow's public transport system.
Alexander Bortnikov, director of the Federal Security Service, or FSB, said Tuesday that one of the 12 suspects, Aslan Baisultanov, had been trained in Syria.
Russian news agencies reported that an FSB official told the court that Baisultanov brought the explosives and detonator to Moscow from Grozny, the Chechen capital.
The FSB official, who was not identified, said the terror attack was aimed at destabilizing Russia and stopping the Russian military airstrikes in Syria against the Islamic State group, the news agencies said. It was unclear how the security service came to this conclusion.
The two other suspects who appeared in court were Elman Ashayev and Mokhmad Mezhidov.
The ISIS-linked terrorist plot highlights the new terror threat to Russia raised by its air campaign in Syria.
President Vladimir Putin has acknowledged the new danger, but insisted that launching the Russian airstrikes in support of Syrian President Bashar Assad's army was necessary to fight ISIS and other militant groups before they pose an even bigger security challenge to Russia.
"If we just stood by and let Syria get gobbled up, thousands of people running around there now with Kalashnikovs would end up on our territory, and so we are helping President Assad fight this threat before it reaches our borders," Putin said in an interview with Rossiya state television broadcast Sunday.
"We must take pre-emptive action," he said. "Of course, there are risks, but let me say that these risks existed anyway, even before we began our operations in Syria."
The U.S. and many others in the West have been dismissive of Putin's reasoning on the Syria conflict, saying the Russians are largely targeting rebels opposed to Assad instead of ISIS. U.S. officials say Russia has directed parts of its air campaign against U.S.-funded groups and other moderate opposition groups in a concerted effort to weaken them.
In an interview with "60 Minutes" that aired Sunday night, President Obama said Putin's actions in Syria won't change his mind about the necessity of forcing Assad to step down.
"We've got a 60-country coalition that isn't suddenly lining up around Russia's strategy," Mr. Obama said. "To the contrary, they are arguing that, in fact, that strategy will not work."
Russian authorities have said that about 2,400 Russians have joined the ISIS militants and voiced concern that they may pose a threat when they return home.
The latest arrests may play into Putin's hands, proving his point that ISIS poses a major threat to Russia and the air raids are a necessary response to the challenge.
A nationwide poll of 1,600 conducted earlier this month by VTsiOM polling agency found that two thirds of respondents supported the Kremlin's decision to launch airstrikes in Syria. The poll had a margin of error of no more than 3.5 percentage points.