Since returning to office in January, President Donald Trump has made a major push to put America’s elite universities on notice over political ideology. But the groundwork for the White House’s stronger stance was laid more than a year earlier.

The president of Harvard on Wednesday defended the university’s decision to sue the Trump administration, adding that the institution “cannot compromise” on core principles like the First Amendment. Harvard took legal action against the Trump administration on Monday over the government’s decision to freeze over $2 billion in federal funding meant for the university after it refused to make the reforms it ordered.

The elite research institution rejected a list of White House demands that it said would undermine its independence.