american citizen. sources tell the south korean news agency yonhap the man was arrested friday at the pyongyang international airport just as he was trying to leave the country. it's unclear why he was arrested, and cnn has not been able to independently verify this information. he reportedly had been in north korea for about one month working on aid and relief programs. >> a korean-american is only identified by his last name, kim. he's believed to be in his late 50s. he's believed to be a former professor. he's the third american currently detained in north korea. a college student and a pastor have been sentenced to hard labor for what pyongyang claims are acts against the country. it is a national day of mourning in afghanistan to honor the soldiers killed in friday's horrific taliban attack. >> that's right. sources say that as many as 140 people died. official figures have not yet been released.