Former National Security Agency (NSA) analyst Edward Snowden, a refugee in Russia, today described the London arrest of WikiLeaks founder Julian Assange as a “black moment” for press freedom.

“Assange’s critics may rejoice, but this is a black moment for press freedom,” he said in his official Twitter account.

Snowden, a refugee in Russia for more than five years after revealing details of wide-ranging national and international U.S. spying programs in 2013, also criticized Ecuadorian authorities.

“The images of the Ecuadorian ambassador inviting the United Kingdom secret police to the Embassy to drag an award-winning journalist out of the building will end up in history books,” he said.

He also recalled that in 2016 the UN Working Group on Arbitrary Detention concluded that the Australian is in a “situation of arbitrary detention.

Snowden said independent UN experts have repeatedly urged the UK to honour its international obligations and let Assange freely leave the Ecuadorian Embassy.