FILE -- In this Oct. 11, 2016 file photo, provided by the Syrian Civil Defense group known as the White Helmets, residents sit amongst rubble in rebel-held eastern Aleppo, Syria. Syrian opposition activists say airstrikes have hit rebel-held eastern Aleppo on Tuesday, Nov. 15, 2016, for the first time in three weeks, fearing it could signal the start of a new government offensive in the northern city. The Britain-based Syrian Observatory for Human Rights says that airstrikes struck three neighborhoods. It had no immediate word on casualties. (Syrian Civil Defense- White Helmets via AP, File)
FILE -- In this Oct. 11, 2016 file photo, provided by the Syrian Civil Defense group known as the White Helmets, residents sit amongst rubble in rebel-held eastern Aleppo, Syria. Syrian opposition activists say airstrikes have hit rebel-held eastern Aleppo on Tuesday, Nov. 15, 2016, for the first time in three weeks, fearing it could signal the start of a new government offensive in the northern city. The Britain-based Syrian Observatory for Human Rights says that airstrikes struck three neighborhoods. It had no immediate word on casualties. (Syrian Civil Defense- White Helmets via AP, File) Credit: Uncredited

Beirut — With a hail of missile strikes, Russian forces announced a major offensive on Tuesday against rebel-held areas in Syria. As the assault unfolded, activists in the crucial city of Aleppo said that their skies were filled with government warplanes and that bombs were raining down.

The Russian Defense Ministry said that it had used its sole aircraft carrier — ordered last week to the Mediterranean Sea in support of Syrian President Bashar Assad — for the first time and that missiles had also been fired from a land-based system inside Syria as well as another Russian warship off the coast.

Activists said the Russian targets appeared to include eastern Aleppo, one of the last urban bastions of factions opposing Assad. But Moscow denied involvement in the attacks on the city, saying it has been nearly a month since Russian forces launched strikes there.

The divided city has become the epicenter of the battle for Syria. The government’s recapture of Aleppo could hasten the fall of remaining rebel strongholds across the country.

Russia’s assault kicked off just hours after Putin and President-elect Donald Trump, speaking by phone, agreed to combine efforts in Syria to defeat what Moscow has said is its enemy in the fight: “international terrorism and extremism.”

President Obama’s administration has been aiding what it sees as moderate opponents of Assad while continuing the fight against al-Qaida’s Syrian affiliate, which in some places has been battling alongside the rebels.

Russia describes all rebel groups as “terrorists,” and Trump’s blanket statements about joining Russia have been seen in Moscow as tacitly supporting this view.