An electronic board flashes the numbers of the foreign exchange rate of the yen against one US dollar at a foreign exchange brokerage in Tokyo on February 13, 2013. - 

No one at the meeting of the world's 20 major economies in Moscow today is actually mentioning the word "war," they prefer the term "unorthodox global monetary policy," but the battle lines are being drawn and the so-called "currency war" is at the top of the G20 agenda.

A currency war is when countries deliberately drive down the value of their currency, making their goods cheaper and therefore giving their businesses a competitive advantage in the global market. And it is what some G20 countries accuse the U.S., Japan and England of creating since they've been flooding their economies with money. For their part, the U.S. and Japan argue they're just trying to drive up domestic demand and promote growth, and that a weaker dollar or yen is an unintended consequence.

According the BBC's Andrew Walker, the G20 meeting probably will not turn out a peace treaty. Instead, an official statement warning against competitive devaluations, that may do little to change the monetary policies of global leaders, is more likely.