MOSCOW — Russia said for the first time on Tuesday that a bomb aboard a Russian charter jet full of vacationers caused the aircraft's destruction more than two weeks ago over 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 spree of deadly attacks across Paris on Friday.
Russia said it had deployed cruise missiles, long-range bombers flying from Russia and other warplanes, releasing the details through a military briefing for President Vladimir Putin and Defense Minister Sergei Shoigu that was televised live nationwide.
"A massive airstrike is targeting ISIL sites in Syrian territory," Shoigu said, using an acronym 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."
Putin and the defense chief were shown sitting in a gigantic, three-story military command center — officially called the National Defense Management Center — with a map of Syria the size of a movie screen on one wall.
In a scene that could have been lifted out of a 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 Russian acknowledgment that a bomb downed the Metrojet Airbus A321, killing all 224 people aboard, came after 17 days of hedging by Moscow, even though it was increasingly clear that Russian investigators had reached that conclusion.
The timing of such a highly orchestrated announcement, coming as 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.
Egyptian officials, by sharp contrast, have repeatedly asserted that it was premature to conclude that a bomb had destroyed the Russian jetliner, with some saying that such an explanation was part of an international conspiracy against their country.
The plane had just departed Sharm el-Sheikh, a Red Sea resort that now is reeling from a loss of tourism. Confirmation that it was brought down by a bomb — presumably smuggled through the Sharm el-Sheikh airport — would represent a devastating blow to Egypt's vital tourism industry, and would undermine government claims that the authorities are prevailing in the war against militants based in the Sinai Peninsula.
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.
On Tuesday, after hours of silence following the Russian announcement, Egyptian officials seemed to be gingerly walking back their previous denials.
Egypt's civil aviation minister said that the committee investigating the crash had not yet reached any conclusions and had "not arrived at any criminal evidence," but a statement from the Interior Ministry pointedly 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. The change was "not easy" for the Egyptian government, especially as President Abdel-Fattah el-Sissi had all but declared victory over militants in Sinai, al-Sayyid said.
At the same time, the Egyptians were trying to avoid any rift with the Russians, given their increasingly close security and economic cooperation, he said. And the Paris attacks, coupled with France's admissions of security gaps, may have helped create the basis for Egypt to admit the possibility of its own failings.
Alexander V. Bortnikov, the head of the Federal Security Service, or FSB, said in remarks to Russia's Security Council Monday night and broadcast nationally on Tuesday morning that "we can say definitely that this was a terrorist act."
An "improvised explosive device" detonated soon after the plane had departed Sharm el-Sheikh, 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 such detail at a live television briefing, left no doubt that the Russians were now intent on showing that 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. Earlier news reports said the Kalibr cruise missiles were fired by submarines for the first time by Russia in a real war.
Military aircraft, including long-range bombers flying from Russia itself, had flown 127 sorties, hitting 266 targets and destroying 140 of them, 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, Gerasimov said.
Putin did not speak much during the briefing, but he ordered one naval commander to coordinate his actions with a French aircraft carrier group that was about to deploy off Syria.
Putin and the French president, François Hollande, had spoken by telephone earlier in the day and agreed to coordinate their military attacks in Syria, the Kremlin announced. The two men are due to meet in Moscow on Nov. 26, it said.
For a second consecutive day, French warplanes hit a command post and a recruitment center for jihadis in the Islamic State stronghold of Raqqa, Syria, the French Ministry of Defense announced on its website, while Russian news reports said a Russian submarine had fired cruise missiles at Islamic State targets in the same area.
Since its intervention in Syria, Russia has focused most of its firepower on opponents of President Bashar Assad of Syria and not the Islamic State. The diplomatic rewards of changing focus and answering the call of Hollande for a united military effort against the Islamic State are already palpable.
A pariah in Western leadership circles since his invasion of Crimea in the spring and his subsequent support of separatists in eastern Ukraine, Putin was suddenly front and center at the Group of 20 summit meeting this week in Antalya, Turkey. For Putin, ending the diplomatic isolation could be an important first step in persuading the West to lift economic sanctions on his wobbly economy that were imposed after those earlier actions.
British and U.S. intelligence agencies had reached the same conclusion as Russia about the cause of the jetliner's destruction within days of the Oct. 31 crash. The Islamic State claimed responsibility within hours, although it did not provide any proof.
Russian crash investigators concluded the bomb contained up to 1 kilogram, or 2.2 pounds, of TNT, Bortnikov said, adding that "foreign made" explosive material was found on parts of the plane and other objects that were examined.
Russia also offered $50 million for any information leading to the capture of those who carried out the attack, and Putin vowed to track them down.
"We will search for them everywhere, no matter where they are hiding," Putin said at a meeting with his security council that was broadcast on national television. "We will find them in any place on the planet and will punish them."