Q+A - How North Korea earns money from arms sales

By Jon Herskovitz

SEOUL (Reuters) - North Korea fired seven ballistic missiles on Saturday, South Korea's defense ministry said, in an act of defiance against the United States as Washington cracks down on the secretive state's weapons proliferation.

Following North Korea's May 25 nuclear test, the U.N. Security Council imposed new sanctions to halt the North's missiles sales, a vital source of cash for the destitute state.

Here are some questions and answers about the North's suspected proliferation activities:

HOW MUCH DOES NORTH KOREA MAKE FROM ARMS SALES?

The U.S.-based Institute for Foreign Policy Analysis estimates that North Korea, with an annual GDP others estimate of about $17 billion, earns some $1.5 billion a year from missile sales. Other studies said the figure may be in the hundreds of millions of dollars, with prior U.N. sanctions and other restrictions cutting into exports.

The United States suspects the North has also sold nuclear know-how, but there are no figures readily available on income.

WHO ARE THE CUSTOMERS?

Since the 1980s North Korea has sold missile systems to Iran, Pakistan, Egypt, Libya, Syria and Yemen, the International Crisis Group said in a report last month. Experts said these include the North's variants of the Scud missile and its mid-range Rodong ballistic missile.