Currency is a funny thing in that it can be influenced by many, many different events not just those we typically associate with the economy or finance. Wars while destructive in nature can (and often do) assist the economy of the nation that is waging the war in question. Recently North Korea attacked South Korea, a nation with close political ties to the United States who has sent a naval destroyer into the ocean near the Korean peninsula.
Since this event the United States Dollar received a boost on the Forex currency exchange and while it will not last in the long term (unless there turns out to be a war) it is certainly an opportunity for a trader to take advantage of in the short term. Pairing the USD with a currency such as the CAD which is relatively stable at the moment is a good idea for a few pips due to the fact that unless there is a war in Korea and the US is involved the USD will drop in value due to a correction.
At present many other nations have taken an interest in North Korea such as China and Japan so the likelihood of an all war on the Korean peninsula is unlikely. Getting in now while the situation is good is key in turning over healthy short term profits since a correction in the Forex currency exchange is guaranteed for the dollar if a war does not occur, peace can also be very good for business.