President Obama, making his first trip to C.I.A. headquarters, acknowledged Monday that agency officials had expressed ‘’understandable anxiety and concern” about his decision to release confidential memos detailing brutal interrogation techniques used by agency operatives, and urged employees not to be discouraged about the ensuing uproar. “Don’t be discouraged by what’s happened in the last few weeks,” the president said. “Don’t be discouraged that we have to acknowledge potentially we’ve made some mistakes. That’s how we learn.” Mr. Obama banned the harsh techniques on his second day in office, and he acknowledged that his decision may have made the job...