SAIPAN, Northern Mariana Islands — WikiLeaks founder Julian Assange pleaded guilty on Wednesday local time to a felony charge of violating the Espionage Act after his organization obtained and published classified military and diplomatic documents in 2010. While pleading guilty, Assange said he should have been protected by the First Amendment, but a U.S. attorney rebuffed that argument and accused him of encouraging people with high security clearances to expose sensitive military and defense secrets that threatened national security.