Russia launched a major military offensive in Syria on Tuesday, hours after President-elect Donald Trump and Russian President Vladimir Putin discussed the need to join forces to combat international terrorism.

"Today we started a large-scale operation to deliver massive fire on the positions of the Islamic State and Jabhat al-Nusra in the provinces of Idlib and Homs," Defense Minister Sergey Shoigu said at a meeting Tuesday with Putin and Russian defense industry representatives.

Trump, who expressed respect for Putin during the campaign, spoke with the Russian leader by phone Monday.

"During the call, the two leaders discussed a range of issues including the threats and challenges facing the United States and Russia, strategic economic issues and the historical U.S.-Russia relationship that dates back over 200 years," the Trump transition team said in a statement.

The Kremlin said Putin congratulated Trump and that the leaders agreed on "uniting efforts in the fight with the common enemy number one – international terrorism and extremism." The Kremlin also pledged to build "dialogue with the new administration on the principles of equality, mutual respect and non-interference in the internal affairs of each other."

Secretary of State John Kerry on Monday discussed Aleppo with Russian Foreign Minister Sergey Lavrov, emphasizing the State Department position that the solution must be political, not military. Hours later the airstrikes began.

The Syrian Observatory for Human Rights said airstrikes early Tuesday shook the provinces of Idlib and beleaguered Aleppo, which has been the focal point in a five-year war between U.S.-backed rebels and troops loyal to Russian-backed Syrian President Bashar Assad.

Some of the strikes appeared to target al-Qaeda affiliates fighting alongside the rebels, the observatory said. An airstrike also hit a hospital in the town of Awejel just outside Aleppo, injuring civilians, the British-based advocacy group said.

The United Nation's World Food Program reported Monday that food production in Syria has hit a record low as "widespread insecurity and unfavorable weather conditions in parts of the country continued to hamper access to land, farming supplies and markets."

Jabhat al-Nusra is an al-Qaida affiliate loosely aligned with the U.S-backed rebels. Russia has blamed rebel ties to terror groups for the dire humanitarian issues in Aleppo. The State Department has acknowledged that "marbleization" of the anti-Assad forces has been a problem.

Shoigu said the airstrikes are focused on ammunition depots, groups of terrorists and their training centers, and facilities being used to manufacture weapons of mass destruction. He said Russia had sent radiation, chemical and biological protection troops to determine the toxic substances used by terrorists.

"Within the past week they used them twice – in one case, 27 people were hospitalized and three died, in the other case 30 people were hospitalized – I mean the Syrian Army soldiers," Shoigu said.

Aleppo activist Baraa al-Halaby told the Associated Press warplanes were firing missiles and helicopters were dropping barrel bombs in Syria’s largest city.

“People are scared. The bombardment is intense,” al-Halaby told AP.