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.

Harvard sued in April, claiming the government freeze violates the university's First Amendment guarantee of free speech and federal law governing administrative rulemaking

Decades-long suspicion of elite universities has evolved under President Trump into a full-scale war – punctuated this week by curbs on the flow of international students to Harvard.