Russia on Tuesday staged a "significant number" of air strikes on the Islamic State group stronghold of Raqqa in Syria, a US defence official disclosed today.
The attacks follow Russian President Vladimir Putin's vow of vengeance over a bomb planted in Russian Metroliner passenger jet that exploded over Egypt last month, killing 224 people aboard (See: Russian airliner crash: search continues, IS claims downplayed).
Putin said on Tuesday that Russia's air campaign in Syria "should not only be continued but should be intensified so that the criminals realize that retribution is inevitable."
"In this work, including the search to find and punish the criminals, we are relying on all of our friends," Putin said. "We will act in accordance with the U.N. Charter's Article 51, which gives each country the right to self-defence. Everyone who tries to aid the criminals should understand that they will be responsible for giving them shelter."
The Islamic State group had claimed responsibility for bombing the Russian plane on the internet following the crash, which were initially downplayed by security anlysts (Egyptian cleric masterminded Russian jet crash?).
The Islamic State group claimed the attack was in retaliation over Russian bombardment of the IS and other groups in Syria.
FSB head Alexander Bortnikov said its experts had determined the crash was caused by a homemade explosive device equivalent to 1 kilogram of TNT, which exploded inside the aircraft.
He said tests showed the explosives had been produced outside Russia, without elaborating
News channel NDTV reported that President Putin has offered a £33-million bounty for the capture of those responsible for the crash.
Meanwhile, the IS has warned that it would also target Putin "at home."
Russia made the announcement the day after meetings with other world leaders in Turkey, where they vowed to work together to combat the Islamic State group.
but did not offer any details to back its claim. While releasing specifics would add credibility, the group may be withholding because its claim is false, because doing so would undermine plans for similar attacks in the future, or because the aura of mystery might deepen its mystique among die-hard followers.
France also invoked an EU treaty provision requesting mutual assistance from other EU countries.
The French defence minister, Jean-Yves Le Drian, said EU partners could help ''either by taking part in France's operations in Syria or Iraq, or by easing the load or providing support for France in other operations,'' reports the Guardian.
France is the first nation to invoke article 42.7 in the treaty, which requires all states to offer aid and assistance ''as they are able''.
All of the people on board, most of them Russian tourists, were killed when the Metrojet Airbus 321-200 crashed over the Sinai Peninsula on Oct. 31, about 23 minutes after taking off from the Red Sea resort city of Sharm el-Sheikh. The plane was headed to St. Petersburg, where most of the passengers were from.
In Cairo, there was no immediate comment on the news from the Egyptian government. State-owned television carried the newsbreak from Moscow, but had no official comment either.
Egypt had resisted British and U.S. assertions that an explosive device was the likely cause of the Russian plane's crash. Later, government officials and the pro-government media shifted their focus away from the cause of the crash to speculating on what they called a Western conspiracy against Egypt and the crushing impact of the crash on the country's vital tourism industry.
Putin vowed to hunt down those responsible for the attack.
"There's no statute of limitations for this. We need to know all of their names," Putin said. "We're going to look for them everywhere wherever they are hiding. We will find them in any place on Earth and punish them."
IS has also claimed responsibility for Friday attacks in Paris that killed 129 people and wounded 350 others.