Mohammad Bagher Ghalibaf, Iran’s parliament speaker, warned the United States against a ground invasion, threatening strong retaliation against U.S. forces and allies.

He said Iranian forces are prepared with missiles and would respond forcefully if American troops enter the region, rejecting any demand for Iran’s surrender from the United States.

He also criticized a U.S. plan delivered via Pakistan, calling it an attempt to achieve through diplomacy what could not be achieved by force.

The Islamic Revolutionary Guard Corps separately threatened to target American and Israeli-linked educational institutions if the United States does not condemn recent strikes on Iranian universities, which it described as legitimate targets, CBS News has reported.

Rising tensions have led some universities in the region to move operations online and prompted warnings about potential risks to institutions associated with the Israel and the United States.