WASHINGTON — The United States and allies launched airstrikes against Sunni militants in Syria early Tuesday, unleashing a torrent of cruise missiles and precision-guided bombs from the air and sea on the militants’ de facto capital of Raqqa and along the porous Iraq border.

American fighter jets and armed Predator and Reaper drones, flying alongside warplanes from several Arab allies, struck a broad array of targets in territory controlled by the militants, known as the Islamic State. American defense officials said the targets included weapons supplies, depots, barracks and buildings the militants use for command and control. Tomahawk cruise missiles were fired from United States Navy ships in the region.

The strikes are a major turning point in President Obama’s war against the Islamic State and open up a risky new stage of the American military campaign. Until now, the administration had bombed Islamic State targets only in Iraq, and had suggested it would be weeks if not months before the start of a bombing campaign against Islamic State targets in Syria.

Bahrain, Jordan, Qatar, Saudi Arabia and the United Arab Emirates took part in the strikes, American officials said, although the Arab governments were not expected to announce their participation until later Tuesday. The new coalition’s makeup is significant because the United States was able to recruit Sunni governments to take action against the Sunni militants of the Islamic State. The operation also unites the squabbling states of the Persian Gulf.