Tom Plant, director of proliferation and nuclear policy at the Royal United Services Institute, told The Sun Online he expects North Korea to unveil a new weapons system soon - but said it may not be on Saturday. He said: "North Korea has a pretty good heritage of giving the incoming US President something to think about so it pushes them up the agenda. "Whether they do that now, or they until November - who knows. "But they certainly have an interest in doing something, I would be surprised if we do not see something of that nature over the next three to four months." The expert said Kim has a "vast array" of weapons in development to choose from, so identifying exactly what it may be is "difficult". Mr Plant said a new submarine-launched missile, which has been the subject for months of speculation amid of flurry of activity at Kim's naval base in Sinpo, would be "very ambitious". He added: "The North Korea issue is not going away, and its going to get harder to resolve as times goes on."