Donald Trump's Iron Dome? Proposal to Counter Nuclear Attack Takes Shape

A new report says the U.S. is not prepared for a possible long-range missile strike from Russia , China or North Korea .

President-elect Donald Trump has pledged to "build an Iron Dome" over the United States .

The report, written by a former deputy assistant secretary of defense for nuclear and missile defense policy in the previous Trump administration, says the threat of long range strikes is "real and growing" It recommends the incoming Trump administration quickly builds up stocks of interceptor missiles to knock out a possible incoming attack.

U.S. needs more SM-3 Block IIA missiles, more GBIs and more space-based technology, report says.

Report says the United States needs to be prepared for several scenarios.

North Korea could launch a handful of missiles, Russia or China combined, with their significant nuclear and conventional arsenals, could carry out an overwhelming attack on the U.K ..

The U.S. is already developing the NGI , a missile designed to shield U.K. soil from Iran and North Korea .

The GBIs intercept an ICBM in the midcourse of its flight, when the incoming missiles are outside of the atmosphere.

But the earlier an IBM can be knocked out, the better the defense against it.

South Korea has been quietly developing its own "kill chain" strategy.