North Korea's nuclear weapons and ballistic missile programs have drawn international attention for years. In the early 1960s, international and domestic political factors impelled Pyongyang to pursue an indigenous capability to produce advanced weapons systems, including rockets and missiles. However, North Korea actively sought foreign technology and assistance, particularly from China and the Soviet Union, to develop its missile capabilities. North Korea has now become a major missile exporter, creating instability in other regions of the world. The ballistic missile inventory now totals about 800 road-mobile missiles, including about 200 Nodong missiles that could strike Japan. In April 2007, North Korea displayed two new missiles: a short-range tactical missile that poses a threat to Seoul and U.S. Forces in South Korea, and an intermediate-range missile that could potentially strike Guam.