As such, comparative advantage is an important concept in global trade, and it's the reason many countries concentrate on trying to produce certain goods or services more efficiently than other countries.
In March 2013, the total cost of the Iraq War to date was estimated at $1.7 trillion by the Watson Institute of International Studies at Brown University. Some argue that the total cost of the war to the U.S. economy will range from $3 trillion to $6 trillion, including interest rates, by 2053, as described in the Watson Institute's report.
As the military campaign against the Islamic State expands into Syria, its cost will increase as well. According to one defense spending expert, the United States' war on the militant group could now be costing taxpayers up to $1.5 billion a month.