Russia and Western countries have traded barbs over a deadly attack by gunmen that killed 137 people in a concert hall outside Moscow.
The US and other Western officials said they had intelligence linking it to an Islamic State branch, and pointed to a warning they gave before the attack. Moscow said the attack was tied to Kyiv, a charge Ukraine denied.
Here is a timeline of events before and after the attack:
March 7
The US embassy in Moscow warns that "extremists" had imminent plans for an attack in Moscow. Hours earlier, Russian security services said they had foiled a planned shooting at a synagogue by a cell from the Afghan arm of Islamic State.
The US embassy urges all US citizens to leave Russia immediately, said people should avoid concerts and crowds and be aware of their surroundings.
US allies including Britain, Canada, South Korea and Latvia repeat the US warning and tell their citizens not to travel to Russia.
March 19
Russian President Vladimir Putin dismisses the "provocative statements by a number of official Western structures regarding potential terrorist attacks in Russia" in a Federal Service Security Board meeting, a Kremlin transcript shows. The actions "resemble outright blackmail and the intention to intimidate and destabilise our society."
March 22
Camouflage-clad gunmen open fire with automatic weapons at concertgoers near Moscow, killing 137 people in the deadliest attack in Russia since the 2004 Beslan school siege.
Islamic State Khorasan, the Afghan branch of the militant group that once sought control over swathes of Iraq and Syria, claims responsibility for the attack, the group's Amaq agency says on Telegram.
The US States condemns the attack and says it has intelligence confirming the claim. It says it had warned Russian authorities in accordance with its longstanding "duty to warn" policy.
March 23
Putin says 11 people have been detained, including the four gunmen, but does not mention Islamic State and says gunmen were trying to escape to Ukraine.
Ukraine's military spy agency denies involvement and says Moscow's suggestion is "another lie from the Russian special services."
Washington issues an updated statement saying Islamic State bears "sole responsibility" for the attack and ruling out any Ukrainian involvement.
March 24
Four suspects are charged with acts of terrorism in Moscow's Basmanny district court, all citizens of the ex-Soviet republic of Tajikistan, according to Moscow courts' official Telegram channel.
March 25
France raises its security alert to its highest level, says it has intelligence linking the attack in Russia to an Islamic State branch that was also behind foiled attempts to attack France in recent months.
Russia's Foreign Ministry questions US assertions that Islamic State was behind the attack, saying Washington is spreading a version of the "bogeyman" of Islamic State to cover its "wards" in Kyiv.
In Washington, the White House insists the attack was not linked to Ukraine, and rejects Russian claims as "just more Kremlin propaganda." White House spokesperson John Kirby says: "We are very vigilant in monitoring this group's activities and their planning, as best we can. ... It was because of the aggressive way which we have been monitoring ISIS that we were able to give the Russians a warning that, in fact, they were heading for a potential terrorist attack in the very near future."
Putin acknowledges that the attack was carried out by Islamic militants, but suggests it was also to the benefit of Ukraine and that Kyiv may have played a role.
—Reuters