GETTY Russian President Vladimir Putin delivers a speech in Moscow today

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ISIS militants sickeningly claimed 'credit' for the Metrojet A321 crash which killed all 224 people on board. Today, Russia admitted it was terrorists who caused the Russian plane crash. It was discovered that traces of a 1kg homemade bomb have been found at the wreckage site. Putin said he was ready to ramp up the fight against terrorists. ISIS, which has established a base in Sinai province, tops the list of potential culprits.

The mass slaughter of Russian citizens by the extremist group threatens to escalate the war in Syria, where Vladimir Putin's warplanes have been bombing for more than a month. Russia has also shown solidarity to France and the West after the Paris terror attacks, with Moscow paying tributes to the victims. Defence and security expert Raffaello Pantucci told Express.co.uk ISIS involvement in the plane tragedy would "only harden Russian resolve that they need to do something stronger".

AP Russian President Vladimir Putin shakes hand with Syria President Bashar Assad in the Kremlim

GETTY Syrians evacuate people from damaged buildings following Russian airstrikes

Russian military chiefs feared a terror attack such as that which took place on Saturday over Egypt would swing public opinion in Russia against the airstrikes. But Mr Pantucci, the director of International Security Studies at the respected Royal United Services Institute (Rusi) think tank, suggested that was not likely to be the case. "Russia has dealt with all sorts of terror attacks at home and the population is fairly resilient to them," he said.

That view was challenged by Igor Sutyagin, a senior research fellow in Russian studies at Rusi. Dr Sutyagin, who specialises in US-Russian relations, said the Kremlin was "already increasing" its airstrikes in the region but that it was unlikely Russia would "dramatically increase" aerial bombardment of ISIS targets as a result of the plane crash.

Russian airliner bombed over Egypt Tue, November 17, 2015 Russian airliner flight 9268 crashed en route from Sharm el-Sheikh to St. Petersburg on 31st October 2015, killing all 224 people on board the vast majority of them Russian tourists. Play slideshow AP 1 of 25 The bomb that was used to blow up the Russian Airliner bound for St. Petersburg, Russia, that crashed in Hassana, north Sinai, Egypt, killing all 224 people on board

GETTY Putin talks with cadets during a street rally

He explained that the best response for Moscow was to "pretend that nothing has happened", adding that a mechanical fault on the plane would be the ideal scenario for Putin, whose ambitions in Syria were to conduct a "remote, bloodless war". "If you do not deliver on what you promise, you are in trouble. That is why they will keep the line that nothing happened but a technical fault," he told Express.co.uk. "We just do not admit that it is somehow related to ISI. Domestically that will be the main problem, they need to maintain that line."