Obtained several secrets critical to development of advanced nuclear weapons, including sensitive missile guidance systems and a so-called rail gun that uses electro-magnetic waves to propel missiles.

CNN: Sources: Report finds China stole 'sensitive' nuclear data

Neodymium magnets can be used in missile guidance systems.

FORBES: Dual-Use Technology, Japan-China Economic Integration, and the New Japanese NSC

The steady perfection of missile guidance has long made nearly everything the left says about nuclear disarmament disingenuous or uninformed, and the advent of metastable explosives creates the prospect of a single B-1 bomber carrying the non-nuclear weapons load of 450 B-17s, the equivalent of 26, 800 100-pound bombs.

CENTERFORSECURITYPOLICY: Center For Security Policy

According to the 2004 Iraq Survey Group report of former CIA chief weapons inspector Charles Duelfer, from about 1999 until the 2003 overthrow of Saddam Hussein, Syria served as the chief broker for weapons deals--including missile components and guidance systems--that Saddam was negotiating with North Korea.

FORBES: Freedom's Edge

Hagel acknowledged a problem with the guidance system of missile interceptors and said further testing would occur this year.

CNN: U.S. to beef up missile defense against North Korea, Iran

He acknowledged a problem with the guidance system of missile interceptors and said further testing would occur this year.

CNN: U.S. to beef up missile defense against North Korea, Iran

Lockheed Martin received a contract in 2007 to extend the life of the missiles until at least 2040, with additional contracts doled out to upgrade the guidance system and refurbish the nuclear warheads the missile carries.

FORBES: The Submarine That Might Save America

Building that larger missile would require major advances in metallurgy, rocket engines, guidance and propulsion, and probably foreign assistance.

CNN: Commentary: North Korean launch not a cause for panic

The NRC guidance divides the lower 48 United States into three regions as to wind speed, missile size, depressurization, etc.

FORBES: Tornados and Nukes -- How Big Can They Get?