Two year ago the South Korean government tried to puchase the Global Hawks and was denied. I guess if you fail once try, try again:
South Korea said Wednesday it is still seeking to buy unmanned aerial vehicles (UAVs) from the United States despite Washington’s previous refusal to sell it the high-altitude spy plane. The defence ministry plans to acquire four Global Hawk UAVs by 2012, a spokesman told AFP. The 45-million-dollar craft can cruise at an altitude of 19,500 metres (more than 64,000 feet) for up to 42 hours and identify 30-centimetre (12-inch) objects on the ground.
South Korea is seeking the planes partly so it can keep a better watch over North Korea, as it takes over greater responsibility for its defence from its ally the United States.
But its request for the Global Hawks was rejected in 2005. The US says that the Missile Technology Control Regime, which covers the unmanned plane, should be revised first.
So why was the Global Hawks denied to South Korea two years ago you may ask? Unsurprisingly, this is why:
The U.S. is thought to have rejected the request for fear that the core technology might be leaked. Some are known to be worried that confidential information collected on North Korea using the Global Hawk might be leaked to the North.
It is pretty much no secret in the military community that anything given or sold to South Korea ends up being leaked to the North and nothing in the last two years has changed this fact. If anything trust between the US and Korea has decreased even more.
Look at who the US did sell the Global Hawk too:
The Defense Acquisition Program Administration said, While continuously requesting the U.S to sell us the Global Hawk, we are also developing a domestic mid-altitude UAV system. However, the mid-altitude UAV system development will be possibly completed around 2015. On the other hand, Japan received consent to buy the Global Hawk last June, and it has already secured budgets and commenced preparations to introduce the Global Hawk into its system.
This is probably the main reason why South Korea wants the Global Hawk, simply because Japan has them.