OREKHOVO-ZUYEVO, Russia As Russia congratulated its forces for foiling an alleged Islamist plot on Moscow, the discovery of the plan also pointed to the growing security threat before the 2014 Winter Olympics.
Monday's killing of two suspected militants and arrest of a third in a sleepy town near Moscow was quickly followed by the killing of one of the leaders of an Islamist insurgency being waged in Russia's North Caucasus.
For President Vladimir Putin, who built his reputation more than a decade ago in a war against rebels in the mainly Muslim Chechnya region, such successes are an opportunity to promote the image of a strong state and rally personal support.
But there is also concern at the Kremlin over suspicions the alleged militants had trained abroad and had been linked to a group in the Central Asian state of Uzbekistan.
With Moscow already trying to quell the insurgency in the North Caucasus, the fear is of a widening threat from better-trained groups before Russia hosts the Winter Olympics next February in the Black Sea resort of Sochi.
A pool of blood and broken glass beneath a shattered second-floor window in the flat which the suspected militants had rented in Orekhovo-Zuyevo, about 85 km (55 miles) east of Moscow, were among the few signs of a gun battle there.
Details were sketchy as to exactly what might have been plotted there or who was involved, with only the official version to go on.
State television kept the story at the top of news bulletins in a sign of the weight being put on the events there. Violence occurs almost daily in the North Caucasus, but trouble involving Islamists close to Moscow has been rare.
The National Anti-Terror Committee raised the possibility that not only had the Russian suspects trained in Afghanistan or Pakistan, but that they could have been linked to the Islamic Movement of Uzbekistan.
"If that is confirmed, it's a significant change," said Murad Batal al-Shishani, an independent analyst on Islamist groups in Russia.
"If the IMU is targeting Russia, it would mean the number of groups that have Russia in their sights is expanding and is no longer limited to the North Caucasus.
"It also means we could see more threats to Russian interests in Central Asia and it would force Russia to increase its presence there if it felt it was being threatened."
The Uzbek group - which the United States has designated as a foreign terrorist organization and which supports establishing strict Islamic rule in Uzbekistan - is not known to have attempted any attack in Russia.
It made no immediate comment.
The three suspects had kept a low profile since renting a flat in March on the upper floor of a modest two-storey building in Orekhovo-Zuyevo, neighbors said.
It was not clear why they might have chosen the town of 120,000, but it is beside a good, straight road to the capital.
"I used to say hello to one of them who looked around 25. I'd see him going out to do the shopping but I never saw the other two," said Oleg Smirnov, an unemployed man of 49 who lived in a flat below the suspects.
"If I'd have known what they were doing, I'd have shot them myself," he said.
Zina Simakova, 16, was watching television when the shooting started at about 4:50 p.m. (0850 ET) in the flat next door.
Her mother, 52-year-old pediatrician Irada Simakova, said: "We saw little of them. They were very quiet. But we heard a strange bang 10 days ago which was reported to police."
The Anti-Terror Committee did not say what the suspects' target had been or when they planned the attack. But the report of the strange noise, which neighbors suspected was an explosion, may have provided the security services with a break.
Many details of the suspected plot and raid were impossible to verify and one security analyst, who declined to be identified, said reports should always be taken "with a pinch of salt" as they could be exaggerated.
The last big attack in Moscow was a suicide bombing that killed 37 people at an airport in January 2011, but since then the leader of the North Caucasus rebels who claimed it says he has ordered a halt to attacks on civilians in Russia.
Kremlin spokesman Dmitry Peskov said Putin had been kept informed as the security services surrounded the apartment bloc in Orekhovo-Zuyevo.
An Anti-terror Committee spokesman said: "Through their decisive actions the law enforcement services prevented an attempt to carry out a terrorist act in the capital of our homeland."
COOPERATION WITH THE UNITED STATES
It was not immediately clear where the suspects came from.
Russia has voiced concerns Islamist violence could spread northward with the withdrawal of most NATO-led combat troops from Afghanistan by the end of 2014.
Russian media cited a name, provided by a source in the law enforcement agencies, which suggested the man in detention, was from the North Caucasus.
State-run media have been giving increasing prominence to Moscow's fight against insurgents as the Olympics approach.
Russia is also trying to build up cooperation with the United States on security matters following the Boston Marathon bombings, given that the suspects had their roots in the Caucasus.
Making the most of any successes against Islamists could help Putin rebuild support after the biggest demonstration against him in more than a decade of power, although protests have dwindled since they began at the end of 2011.
In another apparent success for security forces, investigators said on Tuesday the right-hand man of Russia's most wanted insurgent had been killed by security forces in Ingushetia in the North Caucasus.
Dzhamaleil Mutaliyev masterminded a bombing that killed 18 people at a market in 2010 and was a close aide of Doku Umarov, leader of the outlawed Caucasus Emirate, the Anti-Terrorism Committee said.
(Additional reporting by Thomas Grove in Moscow; Editing by Matthew Tostevin)