Updated 06:16 a.m. Moscow time.
"I can confirm that US military and partner nation forces are undertaking military action against ISIL terrorists in Syria, using a mix of fighter, bomber and Tomahawk Land Attack Missiles," Pentagon Press Secretary Rear Adm. John Kirby said.
"The decision to conduct these strikes was made earlier today by the US Central Command commander under authorization granted him by the commander in chief," Kirby added.
The IS, also known as the Islamic State of Iraq and Greater Syria (ISIS) or the Islamic State of Iraq and the Levant (ISIL), has been fighting against Syrian government since 2012. In June 2014, the group extended its attacks to northern and western Iraq, declaring a caliphate on the territories over which it had control.
Earlier in September, US President Barack Obama unveiled his strategy for defeating the Islamic State militants, which includes the establishment of an international anti-IS coalition. The president also authorized US airstrikes against IS positions in Syria, while simultaneously continuing airstrikes in Iraq, which were launched by the country in August.