WikiLeaks is well-known for dropping surprises. But when the whistleblower organisation posted a tweet yesterday afternoon saying “stand by for an extraordinary announcement,” it is doubtful even one of its 1.5 million followers could have predicted what was coming.

Four hours and forty minutes later WikiLeaks dramatically announced that its editor-and-chief, Julian Assange, was at the Ecuadorian embassy in central London where he had made a request for political asylum. Ecuador’s foreign affairs ministry issued a confirmation, saying it was evaluating Assange’s request. Meanwhile it looked like the country’s foreign minister, Ricardo Patiño Aroca, had already made up his mind as he took to Twitter, posting a series appearing to back the 40-year-old Australian. “We are ready to defend principles, not narrow interests,” he wrote.

Why did Assange take such a drastic course of action? Last week Supreme Court judges ruled he would have to be extradited to Sweden to be questioned over sexual misconduct accusations made against him there in 2010. He has been fighting the extradition for more than eighteen months, principally because he believes that if he is sent to Sweden, he could be held incommunicado and then be ultimately handed over to authorities in the United States, where a Grand Jury is actively investigating him over WikiLeaks’ publication of classified US government documents.

In a statement, Assange said that he was in a “state of helplessness” and felt abandoned by the Australian government, who had failed to intervene in his case. He added that he had been attacked openly by top politicians in Sweden and feared he could eventually face the death penalty in the US for the crimes of treason and espionage.

The timing was unexpected, because the WikiLeaks founder still had the option of asking the European Court of Human Rights to hear an appeal. But in some ways seeking refuge at the Ecuadorian embassy was an obvious choice. Assange interviewed the country’s president, Rafael Correa, recently for his television show, and the two men had a rapport (“WikiLeaks has strengthened us,” Correa beamed). Ecuador previously offered Assange a safe haven in 2010, just a few months before it expelled the US ambassador following WikiLeaks revelations. (It is worth noting, however, the country is not exactly aligned with WikiLeaks ideologically: it has a record on free speech that Human Rights Watch says is the poorest in the region after Cuba.)

Assange will not have taken the decision to ask for asylum lightly. It is a huge step borne out of clear desperation, with massive ramifications to boot. For eighteen months he has been obediently adhering to strict bail conditions – subjected to a curfew forcing him to stay a registered address between the hours of 10pm and 7am, an electronic tag strapped around his ankle that can track his movements. Now Assange is in breach of those conditions and, as a result, the thousands of pounds supporters pledged to secure his release from jail in 2010 may be forfeited.

Police will be actively seeking his arrest – though are currently powerless to do so, as under the terms of the Vienna Convention on Diplomatic Relations an embassy is considered “inviolable.” That means UK authorities are not allowed to enter “except with the consent of the head of the mission.” Assange should therefore be safe so long as he is within the confines of the embassy. If he tries to leave, however, he could find himself in trouble.

Historically, people who have sought refuge in embassies have met different fates. Dissident Chinese lawyer Chen Guangcheng recently fled to the US embassy in Beijing China and negotiated a quick and safe passage out of the country on a flight to New York. But others have not been so lucky. In 1956 a leader of the Hungarian uprising, wanted by Soviet authorities, took refuge at the US embassy in Budapest and ended up spending the next 15 years inside its compound, watched by police around the clock.

For Assange, a man haunted by fears of solitary confinement and a draconian US prosecution, 15 years inside an embassy compound may sound like a preferable option.