The U.S. Justice Department will face off with opponents in a federal appeals court on Tuesday over the fate of President Donald Trump’s temporary travel ban on people from seven Muslim-majority countries, his most controversial act since taking office last month.

Last Friday, U.S. District Judge James Robart suspended Trump’s ban, opening a window for people from the seven affected countries to enter the country.

The 9th U.S. Circuit Court of Appeals in San Francisco will hear arguments over whether to restore the ban from Justice Department lawyers and opposing attorneys for the states of Minnesota and Washington at 3 p.m. PST.

In a tweet on Monday night, Trump said: “The threat from radical Islamic terrorism is very real, just look at what is happening in Europe and the Middle-East. Courts must act fast!”

Trump has said the travel measures are designed to protect the country against the threat of terrorism. He has derided Robart, appointed by Republican President George W. Bush, as a “so-called judge.”

In a brief filed on Monday, the Justice Department said the suspension of Trump’s order was too broad and “at most” should be limited to people who were already granted entry to the country and were temporarily abroad, or to those who want to leave and return to the United States.

Opponents say the 90-day ban barring entry for citizens from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen and imposing a 120-day halt to all refugees, is illegal. The state of Washington argues it has suffered harm, saying some students and faculty at state universities had been stranded overseas because of the ban.

The Republican president’s Jan. 27 executive order sparked protests and chaos at U.S. and overseas airports in the weekend that followed.

All the people who had carried out fatal attacks inspired by Islamist militancy in the United States since the Sept. 11, 2001, attacks had been U.S. citizens or legal residents, the New America think tank said. None came to the United States or were from a family that emigrated from one of the countries listed in the travel ban, it said. (bit.ly/2keSmUO)

Trump faces an uphill battle in the liberal-leaning San Francisco court. Two members of three-judge panel that will hear the arguments were appointed by former Democratic Presidents Jimmy Carter and Barack Obama, and one was appointed by Bush.

Appeals courts are generally leery of upending the status quo, which in this case is the lower court’s suspension of the ban.

Opponents of the ban received far more filings in support of their position than the Department of Justice. Washington state’s challenge was backed by about a dozen friends-of-the- court briefs submitted by at least 17 state attorneys general, more than 100 companies, and about a dozen labor and civil rights groups. About a dozen conservative groups supported the government in three such briefs.