The White House has announced that US President Donald Trump's national security adviser, Michael Flynn, has resigned over his contacts with Russia.
Flynn is alleged to have discussed US sanctions with the Russian ambassador before President Trump took office.
He is said to have misled officials about the conversation.
Earlier, US media reported that the Justice Department had warned the White House about the contacts late last month.
They said that Flynn might be vulnerable to Russian blackmail.
Senior Democrats had called for Flynn to be fired.
