There are growing concerns that North Korea is gearing up for a nuclear weapons test.
The communist nation is responding to tough new U.N. sanctions that followed a missile launch in December.
North Korea's young leader Kim Jong Un is threatening to test long range rockets and says the United States is the ultimate target.
But how likely is it that North Korea has the ability to launch a nuclear weapon that could reach the western United States?
Mark Juergensmeyer, the director of UC Santa Barbara's Global International Studies department, says the test launches could go a long way in showing how close the North Koreans are to having a long-range nuclear missile.
"They probably are able to enrich uranium and are probably able to produce a nuclear device," Juergensmeyer said. "The big issue is the missile capacity to actually do something other than go to a border and drop it there. They actually want to be able to launch it."
A nuclear test in 2009 revealed the North Koreans have a bomb about half as powerful as the one used to destroy Hiroshima in 1945. But for all their firepower the North Koreans lack the ability to make a nuclear weapon small enough to fit on a missile that can reach the U.S. mainland.
China is North Korea's main ally in the region. China says it will drop its financial support if North Korea doesn't drop its test plans.