TEHRAN, Jan. 8 (Xinhua) -- Iran's missile attack on two Iraqi bases housing U.S. troops on Wednesday could signal the beginning of the expulsion of U.S. troops from the region, Iranian officials and experts said.

Iran's Islamic Revolution Guards Corps (IRGC) on Wednesday fired over a dozen of surface-to-surface missiles on the U.S. bases of Al-Asad and Harir Camp to the north of Erbil, Iraq.

Iran not only aims to take revenge on the U.S. for assassinating a senior Iranian commander last Friday, but also force the U.S. troops to pull out from the region.

"To expel the United States from the West Asia, showering of missiles (on the U.S. bases) is an introductory measure," Ahmad Amirabadi, an Iranian political expert, said in an interview.

With the attack, Iran aims "to force U.S. out of the region," he said, adding that the direct Iran-U.S. military clash "is the beginning of the road."

On Wednesday, Iran's Supreme Leader Ayatollah Ali Khamenei urged the U.S. to pull its forces out of the region, hours after Iran launched missile attacks.

"Military operations of this kind is not enough," Khamenei said, adding that "what is important is to put an end to the corruptive presence of the Americans in the region."

"Americans have brought war, sedition, destruction and division to the region. Our region and the nations of our region no longer accept the presence of Americans," the Iranian leader said in a televised speech in Iran's religious city of Qom.

Iranian President Hassan Rouhani said Wednesday that the main reason for the Iranian retaliation against the U.S. for the assassination of Qassem Soleimani, commander of the IRGC's Quds Force, is that "American forces must be expelled from the region forever."

"They (Americans) cut off the arm of Soleimani in this crime. The revenge is that we cut off the U.S. feet in the region," Rouhani was quoted as saying by Tasnim news agency.

Hossein Baqeri, chief of staff of the Iranian Armed Forces, on Wednesday warned that any new offensive by the U.S. will be met with "stronger, more crushing, and broader" response from Iran.

"The time has come for the evil authorities of the United States to realize the Islamic Republic's capabilities and pull the forces of their terrorist army out of the region as soon as possible," he said.