A U.S. analyst says that North Korea’s Sunday rocket launch doesn’t pose a serious threat to the United States nor does it justify the U.S. deployment of an expensive missile defense system.

In a commentary to CNN, Joseph Cirincione, president of the anti-proliferation organization the “Ploughshares Fund,” said that North Korea's missile and nuclear capabilities do not imply it has nuclear intercontinental ballistic missile capability.

In order to make a real nuclear-armed missile capable of reaching the continental U.S., he said the North needs to develop a bigger, longer-range missile capable of atmospheric re-entry and that its warheads must also be miniaturized.

He said the primitive nuclear device tested by North Korea in 2006 was estimated to weigh more than 15-hundred kilograms, which is thought to be much too heavy to be launched by a vehicle similar to the one tested Sunday.

Cirincione said the U.S. should persuade North Korea to scrap its nuclear program in an irreversible way through negotiations — whether direct or within the framework of the six-way nuclear talks.