BEIRUT — The United States bombed a suspected Islamic State staging area in eastern Syria on Wednesday, as U.S. warplanes also hit the militants’ positions across the border in neighboring Iraq, U.S. officials said.

The airstrikes come a day after the U.S. and five Arab allies opened their military operation against the Islamic State group in Syria with more than 200 strikes on some two dozen targets. That campaign, which President Barack Obama has warned could last years, expands upon the aerial campaign the U.S. has already been conducting for more than a month against the extremists in Iraq.

Along with its Arab partners, the Obama administration aims to destroy the Islamic State group, the extremist faction that has through brute force carved out a proto-state in the heart of the Middle East, effectively erasing the border between Iraq and Syria. The United Nations has accused the extremist faction of committing war crimes.

The latest U.S. strikes damaged eight Islamic State vehicles in Syria near the Iraqi border town of Qaim, the U.S. Central Command said in a statement. It also reported hitting two Islamic State group armed vehicles west of Baghdad, as well as two militant fighting positions in northern Iraq.

In a separate statement, Pentagon spokesman Rear Adm. John Kirby said the strikes in eastern Syria hit a staging area used by the militants to move equipment across the border into Iraq.

He did not specify exactly where the air raids took place, but the Iraqi town of Qaim is across the border from the Syrian town of Boukamal, where Syrian activists reported at least 13 airstrikes on suspected Islamic State positions on Wednesday.

The Britain-based Syrian Observatory for Human Rights said it was not immediately clear who carried out the airstrikes in and around Boukamal, but it cited locals as saying the intensity of the air raids was similar to that of strikes on the town early Tuesday by the U.S.-led military coalition.

The U.S.-led campaign against the extremists has drawn a mixed response from Syria’s multitude of rebel brigades, many of whom have been locked in a deadly fight with Islamic State militants since January. But the rebels’ ultimate goal is to topple Syrian President Bashar Assad, while the U.S. is focused on defeating the Islamic State group.