North Korea's aging air defense system is getting an upgrade by purchasing 5,000 SA-18 (Igla 9K310) portable air-to-surface missiles. Russia is charging $5,000 for each missile and launcher and $3,700 for replacement missiles. North Korea has some older SA-7b portable SAMs and a motley collection of ancient SA-2 and SA-3 high altitude SAMs. While most U.S. warplanes operate at 5,000 meters, outside the range of the SA-18. But if war came to Korea and the situation got desperate, some American aircraft would come down lower to cause greater damage, and become vulnerable to the SA-18.