No cruises will be leaving U.S. coasts for a month. President Trump tweeted Friday evening that Carnival, Norwegian, Royal Caribbean and MSC were suspending outbound cruises for 30 days, at his request.

At my request, effective midnight tonight, Carnival, Royal Caribbean, Norwegian, and MSC have all agreed to suspend outbound cruises for thirty days. It is a great and important industry – it will be kept that way! — Donald J. Trump (@realDonaldTrump) March 13, 2020

The tweet came after a steady parade of cancellation announcements from the major cruise lines.

Royal Caribbean said Friday it was suspending U.S. cruises at midnight in response to the spreading coronavirus, just as MSC Cruises canceled all cruises leaving Miami through the end of April.

Royal Caribbean cruises leaving U.S. ports before midnight will keep operating, and those still at sea will complete their itineraries, the company said. International cruises will not be affected. The company had previously canceled cruises departing from China and tried to deny boarding to anyone traveling through the country. where the virus first started to spread.

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"We understand the gravity of the public health crisis confronting the country. And this is our part to play," the company said in a statement.

The day before, Princess Cruises halted service on all 18 of its cruise ships for 60 days. Viking cruise lines announced it would suspend all river and ocean cruises until April 30, and Disney Cruise Lines canceled all departures through the end of March.

Mr. Trump and Vice President Mike Pence pledged support for the industry at a press conference Friday afternoon, although they did not share details of what that support might look like.

"The American people cherish our cruise line industry," said Pence. "We want to work with the cruise line industry to ensure that when we come through this ... cruise lines are safer than ever before and can prosper for years to come."

Cruise lines have been battered during the coronavirus outbreak, which has infected more than 130,000 people worldwide and killed more than 5,000. Shares of Royal Caribbean have fallen 75% over two months. Carnival Cruise Line, which owns Princess Cruises, has seen its stock price 65%.

Princess Cruises has struggled to contain outbreaks on its Diamond Princess and Grand Princess ships. Nearly 700 people contracted the coronavirus on the Diamond Princess, where they were quarantined in a Japanese port. At least 21 passengers on the Grand Princess tested positive for the virus while the ship was moored off the coast of California.

Princess Cruises customers whose trips are canceled will be issued credit that can be used on a future cruise though May 1, 2022, the company said. They also may request a cash refund. Viking customers will also receive either a credit for future use or a full refund.

The State Department this week advised Americans to avoid cruises in light of the coronavirus outbreak. The U.S. Centers for Disease Control and Prevention also urged people to "defer all cruise ship travel worldwide."

In a sign of the financial battering the cruise industry is taking, Royal Caribbean told CBS MoneyWatch it is laying off contract workers for "special projects" in order to "reduce operating expenses."