Courtesy Arnie Fagan(NEW YORK) -- The State Department has been undertaking an unprecedented global operation to bring home Americans left stranded by governments shutting their borders and canceling international flights to stem the spread of the novel coronavirus.

But even after weeks of repatriation flights, there are still some 25,000 U.S. citizens in need of help, according to the head of the repatriation task force at the department, which has been criticized by many stranded Americans who have complained it was unresponsive or slow to act.

For many Americans, the sudden border closures and canceled flights have also torn their families apart, unable to travel abroad to meet loved ones stuck overseas and not allowed to travel to the U.S.

Early last month, Arnie Fagan had to travel to his hometown of Columbia, Missouri, for business, leaving his girlfriend Vilayvanh Soulinthong and their 13-month old daughter Jasmine Fagan behind in Udon Thani, the provincial capital in northeast Thailand where Fagan has lived for the last three and a half years.

"Thailand was my version of paradise. Unfortunately, right now, it's turned into my version of hell," Fagan said in an interview on Tuesday.

Two weeks after he left, the Thai government sealed off the country's borders, prohibiting outsiders like Fagan from traveling in without confirmation that they have tested negative for COVID-19, the disease caused by the new coronavirus. Like many Americans, Fagan has been unable to secure a test -- and instead hoped to get Soulinthong and Jasmine to the U.S.

Soulinthong, however, is not an American citizen and needs a visa, but visa services at U.S. embassies and consulates around the world have been suspended except for "life or death emergency" applications.

His voice choking with emotion, Fagan told ABC News that the family has even considered plans to try to hand off Jasmine at Bangkok's airport to try to keep her safe.

"We'd already decided that if I needed to take the baby, that she was going to leave the baby with me and go back to Laos. But that's not even a possibility, that's not even a possibility. What horrible decisions you have to make at a time like this, a global crisis -- decisions you wouldn't ever think in your wildest imagination that you'd have to make," he said.

Fagan's family was able to secure an emergency visa appointment, but not until June -- with the risk of COVID-19's spread worsening in Thailand, a country with a substandard health system. By then, what few international flights are still departing Thailand could be grounded, and the U.S. embassy said in its latest guidance Tuesday that it is not considering chartering flights to repatriate U.S. citizens at this time.

With the clock ticking, Fagan finally heard back from embassy officials late Monday, saying they helpfully provided him detailed instructions on what other information Soulinthong's visa application needs. He said he hopes they may be able to expedite her appointment and secure a visa soon, but he fears they may deny her a visa on the suspicion that the family is trying to move to Missouri full-time.

"We had a wonderful life. We want to go back to that," he said, denying that was the case.

The State Department is unable to comment on individual cases because of privacy laws, but Ian Brownlee, the head of the repatriation task force, urged any Americans to "get off the fence" and make plans to return to the U.S. or be prepared to "remain where (they are) for an indefinite period of time."

"We are committed to helping U.S. citizens return home," Brownlee, who serves as principal deputy assistant secretary for consular affairs, added Tuesday.

To date, Brownlee's task force has helped U.S. missions in over 75 countries bring nearly 46,000 Americans back to the U.S. over 449 flights. But he told reporters Monday that there are between 24,000 and 25,000 still registered with the local U.S. embassy seeking help.

One of the greatest concentrations is in India, which closed its borders much later than many other countries, but where some 7,000 Americans have registered with the U.S. embassy. But given the quickly-shifting situation, the U.S. mission is having difficulty reaching people; out of 800 Americans called over the weekend and offered a seat on a flight out, only 10 said yes, according to Brownlee.

Still, there are at least 80 more flights from around the world to come, including five from India and at least one from Russia, which closed its borders over the weekend. Brownlee said the U.S. still doesn't have a clear answer on why an Aerolot flight Friday from Moscow to New York was halted, but in an "inexplicable, last-minute reversal," the airliner was able to reschedule it for Tuesday, leaving that evening "filled with U.S. citizens," according to U.S. embassy spokesperson Rebecca Ross.

A U.S.-chartered flight will also depart Thursday to fly back to the U.S. through London, Ross said.

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