The U.S. State Department is set to announce a sweeping travel advisory over the coronavirus | Mandel Ngan/AFP via Getty Images State Department warns Americans: Don’t travel abroad, come home if overseas Americans are to be instructed not to travel abroad.

The U.S. State Department on Thursday issued an extraordinary advisory urging Americans not to travel overseas, to return to the United States if they can or to otherwise shelter in place, a move that comes amid concerns about the coronavirus pandemic.

The Level 4 advisory for all international travel appears to be unprecedented and is the most severe such warning issued by the department. POLITICO first reported the plans for the announcement earlier Thursday.

Numerous U.S. citizens are already stuck in limbo abroad, and the new guidance threatens to create further anxiety and confusion among travelers. U.S. lawmakers and others have raised questions about the State Department’s ability to aid Americans overseas, but in the new guidance, the department makes clear U.S. citizens shouldn’t count on it to help.

“Have a travel plan that does not rely on the U.S. government for assistance,” the travel advisory tells Americans who decide to go overseas or are already there.

According to several people familiar with the situation, Secretary of State Mike Pompeo approved raising the advisory from its previous status of Level 3. That earlier advisory merely encouraged Americans to reconsider travel abroad.

The State Department press office did not respond to requests for comment, but announced on Thursday that U.S. passport agencies will only accept applications from customers with life-or-death emergencies who plan to travel within 72 hours.

Several current and former U.S. diplomats, some of them with several decades of experience, said they do not recall such a travel advisory ever being issued in the past.

The guidance came after seven weeks of steadily increasing restrictions on U.S. travel, following President Donald Trump's move to limit travel from China at the end of January.

Other countries have closed their borders and imposed further travel restrictions as the virus has spread beyond Asia to Europe and the Western Hemisphere.

There are more than 10,000 confirmed coronavirus cases in the United States, across all 50 states and Washington, D.C.

The World Health Organization on Thursday said that there are more than 191,000 confirmed cases across more than 150 countries; an unofficial tally by researchers at Johns Hopkins University pegs that number still higher.

A State Department official based overseas expressed concern about the pending advisory, saying he worried it would cause panic among Americans. The official pointed out the difficulties of finding flights under the current conditions.

Likely thousands of Americans remain stranded abroad, caught between travel bans and massive airline flight cancellations.

Some Americans are stranded in countries such as Guatemala, which has issued a ban on any flights coming or going, and others are having to pay dearly for what flights are left, often transiting through several countries before finding a way back home.

And the State Department has largely been absent, according to interviews with several Americans stranded abroad, who reported receiving no help from U.S. embassies.

Stephanie Marlin was in Guatemala City visiting a friend when the Guatemalan government closed down its borders, a day before her flight was scheduled to take her back to Nashville.

She said she had communicated multiple times with Delta Air Lines about her flight, which was supposed to leave on Tuesday. Delta assured her that she was “gold” and that her flight would leave as planned.

“I really blame the airlines because I could have left earlier and would have left earlier,” Marlin told POLITICO.

The U.S. government hasn’t been much help either. In her first attempts to reach the embassy there, Marlin said she repeatedly got an emailed form response which offered no actionable help. When she called an emergency number, it simply played a recording with the same information.

It wasn’t until she had a friend get in touch with the office of her member of Congress, Jim Cooper, that she was able to speak to a human at the embassy. But even then, the embassy employee said they were powerless to do anything given Guatemala’s border shut down.

Members of Congress said they’re trying to handle pleas for help from constituents and have been pushing the State Department to figure out how to get Americans home.

Sen. Bob Menendez (D-N.J.), ranking member of the Foreign Relations Committee, led a letter from 9 Democrats on Wednesday asking the State Department to step up its efforts to help those stuck abroad.

“We seek an immediate clarification regarding your current efforts to facilitate the return of Americans to the United States, whether by commercial airline flights, charter flights, or other means,” the letter reads.

Virginia Sen. Mark Warner also reached out to Pompeo on Wednesday, saying he's heard from "an alarming number of Virginians" unable to return home.

His spokesperson, Nelly Decker, said the Virginia Democrat’s office was assisting upward of 20 Virginians around the world “with the number growing almost hourly."