Thursday’s Aeroflot flight to Havana closed its doors without any sign that American fugitive Edward Snowden was aboard, according to reporters camped out near the gate, raising questions about how much longer Snowden might remain in suspended animation in the transit zone at Sheremetyevo Airport.

The 30-year-old former National Security Agency contractor who revealed a secret U.S. surveillance program reportedly arrived from Hong Kong on Sunday with plans to travel onward to Ecuador, where he has applied for asylum.

Later Thursday, officials in Ecuador, who had been issuing welcoming statements, changed their tone and began suggesting obstacles that might explain Snowden’s lingering presence in Moscow. Although an Ecuadoran diplomat — apparently in London — had issued Snowden a safe-conduct pass, it had not been authorized by higher ups and was not valid, government officials said, according to an Associated Press report from Quito.

Although Ecuador has been portraying itself as a plucky freedom-of-speech-loving country standing up to an overbearing United States, it may be reluctant to engage in an all-out battle that would endanger trade between the two countries.

Without some kind of travel document — his U.S. passport was revoked — Snowden would not be able to buy an airline ticket. Meanwhile, Russia has made it clear that while it does not want to carry out U.S. wishes to expel him, neither does it want to take the more confrontational decision of admitting him. Snowden was fast becoming a man wanted by only one country — his own, which he is fleeing after being charged with violating espionage laws.

Despite relentless searching by scores of reporters questioning everyone in sight and buying tickets for the long flight to Havana, Snowden has not been seen at the Moscow airport. One news agency sent its photographer on the flight to Havana on Thursday — for the second time this week.

On Tuesday, Russian President Vladimir Putin confirmed that Snowden was in the airport’s transit zone, an area where a passenger can stay without a visa to enter the country. Putin said Russia had no intention of extraditing Snowden but was not eager to keep him either.

“Mr. Snowden is a free man,” he said. “The faster he chooses his ultimate destination, the better for us and for him.”

One theory went that Russia was taking the opportunity to question him. But Putin denied Russian security agents are speaking with Snowden, as did Julian Assange, the WikiLeaks founder who assisted Snowden’s journey to Moscow from Hong Kong.

The next scheduled flight from Moscow to Cuba leaves Saturday.

Passengers can remain in the airport transit zone for 24 hours without a visa; after that they must get a transit visa, which does not permit them to leave the zone. A part-time consulate operates in the zone to process requests.

Life in the transit zone is not too onerous. Although Terminal F, where Snowden arrived from Hong Kong, was built in the Soviet era, it has been remodeled over the years and is attached to new, state-of-the-art Terminals D and E, where rooms can be rented in a capsule hotel and Burger King and TGI Friday’s can sustain an American burger and snack food habit.