There are reports that North Korea is preparing for another nuclear test. The secretive state has already detonated two nuclear devices. The South Korean broadcaster YTN reported that Pyongyang has begun preparations for a third nuclear test last month.<br/> <br/>Quoting an unnamed diplomatic source, it said the detonation could come as early as next month. <br/> <br/>Experts say another test will improve North Korea's ability to make nuclear weapons but will diminish its supply of fissile material. North Korea's first two nuclear tests were considered only partial successes at best.<br/>