MOSCOW — Russia said for the first time on Tuesday that a bomb aboard a Russian charter jet full of vacationers had destroyed the aircraft that crashed more than two weeks ago on Egypt’s Sinai Peninsula, and the Kremlin responded immediately by escalating airstrikes across Syria.
The Russians said they were coordinating their military campaign with France in sharply ratcheting up attacks on Syrian territory, especially areas held by the Islamic State, the militant group that has asserted responsibility for destroying the Russian jetliner and for the deadly attacks across Paris on Friday.
The timing of such a highly orchestrated announcement, after an outraged France had already started striking Islamic State targets and had called for a united front against the group, suggested that the Kremlin was using the moment to help rebuild frayed relations with the West.
The Kremlin also announced that President Vladimir V. Putin and his French counterpart, François Hollande, had spoken by telephone, had agreed to coordinate military attacks in Syria and will meet on Nov. 26 in Moscow.
Interactive Feature | What We Know and Don’t Know About the Russian Plane Crash A Russian flight crashed in the Sinai Peninsula in Egypt on Oct. 31, killing all 224 people on board. Officials are investigating what might have caused an explosion that brought down the plane.
In a military briefing for Mr. Putin and Defense Minister Sergei Shoigu that was televised live nationwide, it was announced that Russia had deployed cruise missiles, long-range bombers flying from Russia and other warplanes.
“A massive airstrike is targeting ISIL sites in Syrian territory,” Mr. Shoigu said, using one of the acronyms for the Islamic State. “The number of sorties has been doubled, which makes it possible to deliver powerful pinpoint strikes upon ISIL fighters all throughout the Syrian territory.”
Russia acknowledged that a bomb downed the Metrojet Airbus A321, killing all 224 people aboard, after 17 days of hedging, even though it was increasingly clear that Russian investigators had reached that conclusion.
Mr. Putin and his defense chief were shown sitting in a three-story military command center with a map of Syria the size of a movie screen on one wall. In a scene that could have been lifted from a James Bond film, scores of military men, many wearing headsets, were lined up in desks on the main floor and overhead balconies, all facing the screen.
The crash site of the Russian jetliner in Egypt’s Sinai Peninsula in October.
MAXIM GRIGORYEV / RUSSIA’S EMERGENCY MINISTRY, AGENCE FRANCE-PRESSE — GETTY IMAGES
Egyptian officials have repeatedly asserted that it was premature to conclude that a bomb had destroyed the Russian jetliner, with some saying such an explanation was part of an international conspiracy against their country. But Egypt’s position has become harder to maintain in recent days as the Russian government, one of its closest allies, gave increasing indications that it believed a bomb was the most likely cause. The Russians moved to sever almost all air links with Egypt.
The plane crashed minutes after departing Sharm el Sheikh, a Red Sea resort now reeling from a loss of tourism. Russia’s confirmation that the plane was felled by a bomb — presumably smuggled through the Sharm el Sheikh airport — could further weaken Egypt’s vital tourism industry, and undermines government claims of progress in vanquishing militants based in Sinai.
On Tuesday, after hours of silence following the Russian announcement, Egyptian officials seemed to be gingerly walking back their denials. Egypt’s civil aviation minister said the committee investigating the crash had “not arrived at any criminal evidence,” but a statement from the Interior Ministry included the possibility of a “terrorist attack,” while announcing enhanced security measures at airports.
“This is the first time that the Egyptian authorities admit the possibility that whatever happened to the Russian plane was a terrorist attack,” said Mustapha Kamel al-Sayyid, a political science professor at Cairo University and the American University in Cairo. While the change was “not easy” for the Egyptian government, he said, it appeared to reflect an attempt to avoid any rift with the Russians.
Alexander V. Bortnikov, the head of the Federal Security Service, said in remarks to Russia’s Security Council on Monday and broadcast on Tuesday morning that “we can say definitely that this was a terrorist act.”
An “improvised explosive device” detonated soon after the plane took off, he said, adding that “the plane disintegrated in midair, which explains the widely scattered fuselage pieces.”
The Russians did not acknowledge that the Islamic State had planted the bomb. But the Russian attacks that followed on parts of Syria held by the Islamic State, presented in the live television briefing, left no doubt that the Russians were intent on showing they blamed the group.
Russia fired 34 cruise missiles from the eastern Mediterranean, hitting more than a dozen targets in Aleppo and Idlib, said Gen. Valery Gerasimov, the Russian military’s chief of staff.
Military aircraft, including long-range bombers flying from Russia, flew 127 sorties, hitting 266 targets and destroying 140, the defense minister said. The Russian Air Force deployed in Syria has flown almost 2,300 combat missions since the attacks started 48 days ago, General Gerasimov said.
As Russia increased strikes on the Islamic State, however, Russian forces continued to hit insurgents elsewhere in Syria who do not belong to that group and who have even fought against it and received American support — underscoring the complexities international powers face in working together in the Syria conflict.
The Russians did not specify the locations of their strikes. But insurgents and residents in Syria reported Russian aerial assaults where the Islamic State has no presence, in the towns of Saraqeb, in Idlib Province, and Atareb, in western Aleppo Province.
Mr. Putin was shown on television ordering one naval commander to coordinate with a French aircraft carrier group and to “work together as allies.”
France’s defense minister, Jean-Yves Le Drian, also speaking on Tuesday on the TF1 channel nightly news, said 10 French fighter jets had conducted airstrikes against the Islamic State in the Syrian city of Raqqa. It was the third time since the attacks in Paris that France targeted Islamic State installations there.
Since its intervention in Syria, Russia has focused mostly on opponents of President Bashar al-Assad of Syria and not the Islamic State. The diplomatic rewards of changing focus and answering the call of Mr. Hollande for a united military effort against the Islamic State are already palpable.
A pariah in Western leadership circles since his invasion of Crimea last year and his support of separatists in eastern Ukraine, Mr. Putin was suddenly front and center at the Group of 20 summit meeting this week in Antalya, Turkey. For Mr. Putin, ending the diplomatic isolation could be an important first step in persuading the West to lift sanctions on his wobbly economy imposed because of the Ukraine dispute.
Mr. Bortnikov, the head of the head of the Federal Security Service, said crash investigators estimated that the Metrojet bomb had been composed of up to 1 kilogram, or 2.2 pounds, of TNT. He added that “foreign made” explosive material had been found in the wreckage.
Russia also offered $50 million for any information leading to the capture of the bomb plotters.
“We will search for them everywhere, no matter where they are hiding,” Mr. Putin said at a meeting with his security council broadcast on television. “We will find them in any place on the planet and will punish them.”