The US military and partner nations from the anti-ISIS coalition have launched the first attacks on Islamic State targets in Syria, the Pentagon has confirmed.

Airstrikes against Islamic State targets are currently underway in Syria, according to a Pentagon official. The strikes reportedly involve a mix of fighter, bomber, and tomahawk land attack missiles.

"I can confirm that US military and partner nation forces are undertaking military action against ISIL (ISIS/IS) terrorists in Syria using a mix of fighter, bomber and Tomahawk Land Attack Missiles," Pentagon Press Secretary Rear Admiral John Kirby said in a statement.

US military & partner nation forces have begun striking ISIL targets in Syria using mix of fighters, bombers and Tomahawk missiles. — Rear Adm. John Kirby (@PentagonPresSec) September 23, 2014

"The decision to conduct theses strikes was made earlier today by the US Central Command commander under authorization granted him by the commander in chief. We will provide more details later as operationally appropriate," he added.

According to NBC News, the US military is planning to attack up to 20 targets in Syria, including “training sites, headquarters of Sunni fighters and troop encampments.”

A US official told ABC News that up to 20 locations have been targeted in the airstrikes in and around Raqqa. Tomahawk missiles have been fired from at least one ship in the Red Sea. The source also said that Arab nations participating in the airstrikes will be dropping bombs.

According to Jonathan Karl, chief White House correspondent for ABC News, five Arab nations are taking part in the first round of airstrikes in Syria: Jordan, Saudi Arabia, Bahrain, Qatar, and the United Arab Emirates. A US official speaking to Reuters confirmed the participation of Arab partners in the attack, but refused to specify who those partners were.

CENTCOM says the decision to conduct airstrikes was made under authorization granted by the US president.

The decision to conduct these strikes was made earlier today by CENTCOM commander under authorization granted him by the president. — U.S. Central Command (@CENTCOM) September 23, 2014

The Pentagon will not provide further details on the operation “until later,” according to Reuters.

U.S. military and partner nation forces are undertaking military action against ISIL terrorists in Syria. — U.S. Central Command (@CENTCOM) September 23, 2014

Given that these operations are ongoing, we are not in a position to provide additional details at this time. — U.S. Central Command (@CENTCOM) September 23, 2014

The attack follows President Obama’s speech earlier this month, during which he said that the US was prepared to “conduct a systematic campaign of airstrikes” against Islamic State terrorists “wherever they are.”

“That means I will not hesitate to take action against ISIL (ISIS/IS) in Syria as well as Iraq,” Obama said on September 10. The US military has already carried out over 200 strikes on Islamic State targets in Iraq.

Last Tuesday, US Defense Secretary Chuck Hagel confirmed that the US Central Command has a plan to take “targeted actions against ISIS safe havens in Syria,” including striking infrastructure. The US will also train and equip 5,000 members of the Syrian opposition to fight militants from IS. The so-called ‘moderate’ opposition is seen by the US as a legitimate power in Syria since the Assad government has long lost all its legitimacy, according to US officials.

More than 40 nations have said they will participate in the anti-Islamic State crusade, with more than 30 nations offering military support, according to Hagel.

The Syrian government was willing to cooperate in coordinating strikes on Islamic jihadists, which the country has been battling for over three years, but US officials rejected any possibility of such cooperation. Any strikes on Syrian soil without Damascus’ consent will be considered an act of aggression, Syria has warned.

Washington should respect the sovereignty of Syria in its attempts to deal with the Islamic State, Russia has warned repeatedly. Moscow previously expressed concern that US airstrikes may target not only the Islamic State, but also government forces loyal to President Assad.

In a telephone conversation with UN Secretary General Ban Ki-moon on Monday, Russian President Vladimir Putin stressed that airstrikes on terrorist targets in Syria should not be carried out without the consent of the Syrian government.