NOTE: The State Department is urging all Americans stranded overseas to enroll in the Smart Traveler Enrollment Program (STEP) at step.state.gov so that they receive the latest information, including on possible repatriation flights, from the local U.S. embassy. Americans can also call the department and its new repatriation task force at 888-407-4747 within the U.S. or 202-501-4444 outside the U.S.
With thousands of Americans still stranded overseas after flights were canceled and borders shut to stem the spread of novel coronavirus, the State Department says it is working overtime to get them home -- even as many of those Americans grow frustrated and angry at the slow U.S. response or the unresponsiveness of local U.S. embassies.
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That's still less than half of those who have reached out to U.S. embassies and consulates around the world asking for help -- a total of at least 13,500 Americans, according to the senior official. To that end, there will be 16 more repatriation flights in the next five days, they added, without offering details on which countries.
The department and its new repatriation task force, led by Principal Deputy Assistant Secretary for Consular Affairs Ian Brownlee, are focused on evacuating the most vulnerable first -- those at higher risk of contracting the virus, known as COVID-19, or -- like many Americans who have contacted ABC News -- those running out of life-sustaining medications or food.
But the senior official said they cannot guarantee that they will be able to reach every American.
"I'm hesitant to give a guarantee we can move every single person," the senior official said, especially those in the "most remote locations."
Instead, they urged Americans who can still travel commercially to do so immediately or be prepared to hunker down where they are -- but for thousands, it's already too late.
To carry out this "unprecedented" operation, the official said, the U.S. government is using a "variety of means," including aircraft from the Departments of Defense and Homeland Security. That includes an Air Force aircraft that picked up a women's football team and others from Honduras late last week, and DHS planes that are deporting migrants from the U.S. to Central America and then turning around to bring U.S. citizens home.
But the department is focusing its efforts on chartering commercial aircraft, with the senior official saying that was the most "efficient way." These are paid for using an emergency State Department fund and money collected from those Americans who are repatriated. No one has to pay up front, but they are required to sign a promissory note with a specific sum.
"'Whole of government' is a cliche. This is more of a whole of possibility effort to get people out," said the senior official, briefing reporters Monday, "so no option is foreclosed."
To arrange these flights though, the department has to get permission from local governments, made even more difficult after they've closed their borders, and from U.S. authorities at DHS and the Federal Aviation Administration. The task force has been working around the clock to do that, the official said, for chartered flights arranged by the U.S. or by private companies and citizens.
But it's still unclear how the department chooses which method, in which country and who gets a seat, beyond focusing on the most vulnerable. The State Department did not respond to questions about that on Monday.
After the U.S. military used a military cargo plane to evacuate the women's football team and others from Honduras, two American missionaries in the country told ABC News that they were enrolled in the STEP system with the embassy, but were never offered a seat on a repatriation flight.
"I understand the U.S. is going through a bunch right now, but in our eyes, the fact that they already got a bunch of people out on two C-130's leaves us asking, 'Can you just do one or two more trips?" said Jonathan Garcia, whose flight with American Airlines was canceled after the airliner was forced to halt all flights from Honduras until mid-May. "As of right now, we really are stuck until the government helps us out."
While military aircraft deployed to Honduras, none have been used in Peru, where roughly 2,000 Americans have been stranded by the government's sudden closure of borders and halt to domestic travel.
"This is a very stressful time for all, and it is even more stressful being in a foreign country away from family," said Kimberly Gleason, whose two daughters are stuck in Peru, where one was studying abroad and the other was visiting her. "We are all counting on the help of the United States president to do the right thing and to organize a flight out of the country as soon as possible."
Making matters more confusing for so many is the unresponsiveness of the local U.S. embassy or consulate in many of the countries where Americans are stranded and have reached out to ABC News, including Peru, Ecuador, Namibia, Madagascar, Morocco, Indonesia, Australia and Argentina.
"The Trump administration has been completely unresponsive and uncaring about Americans stuck in Peru," said Michelle Schmitt, whose husband Henry and their friend Alan Studley have been stuck in Lima. "There are people there who are in need of money, medicine and a way out. ... Americans are starting to lose hope down there."
These U.S. missions are reportedly overwhelmed by the need and are usually only reaching out to Americans enrolled in STEP once travel options like flights have been arranged. But the lack of response has left many confused as to what, if any plans, are being made to help them.
"The system is working," the senior official said in defense of STEP, after receiving an alert from the embassy in Lima during the briefing.
All last week, as Americans were panicking, that embassy repeatedly referred folks to commercial airliners, even though airspace had already been shut down and flights canceled. Now, two flights have carried a couple hundred people out, with more on the way, the embassy said Monday in its most recent alert.
But the situation there is growing more difficult by the day as the Peruvian government struggles to contain its novel coronavirus outbreak, which has now forced the closure of Lima's international airport. Instead, the government is relying on the airport's military side, which has much less capacity.
The senior official said the U.S. is still awaiting authorization from Peruvian authorities for more flights in and to shepherd hundreds of Americans from remote cities like Cusco and Iquitos to Lima to fly back to the U.S.
ABC News' Matthew Claiborne contributed to this report.