US Director of National Intelligence James Clapper has submitted his letter of resignation, he has told a congressional panel.

He told the House Intelligence Committee that "it felt pretty good".
The 75-year-old top American spy had been expected to step aside, as President-elect Donald Trump prepares to appoint his own officials.
Analysts believe that he is sending a signal to the Trump administration that they must now speed up the transition.
"I submitted my letter of resignation last night which felt pretty good. I've got 64 days left," he told the committee, indicating that he would stay on in the post until President Barack Obama leaves office.
In a profile published by Wire Magazine only hours before his announcement, he defending espionage, saying that he never questioned the morality of his profession.
In his role, he has often been in the position of defending the National Security Agency (NSA).
Its image was badly damaged after Edward Snowden revealed how they collect information on American citizens.