President Donald Trump vowed Monday to prevail in his clash with Harvard and again threatened to take away billions in funding from the university.

For weeks, the Trump administration has been waging a war against Harvard University, releasing a series of conflicting demands, suggesting pulling the school's tax-exempt status, and barring the school from taking international students.

A group of 18 leading US research universities, including Princeton, MIT, Caltech and Johns Hopkins, asked a federal judge for permission to file legal arguments in support of Harvard University in its high-stakes showdown with the Trump administration over more than $2 billion in frozen grant money.