Technology for ballistic and cruise missiles is advancing in countries from North Korea and Iran to Russia and China, increasing potential threats to the U.S. even if those missiles don't carry nuclear warheads, a new Pentagon report states.

"Many countries view ballistic and cruise missile systems as cost-effective weapons and symbols of national power," defense intelligence agencies said in the report obtained by Bloomberg News in advance of its release. "Many ballistic and cruise missiles are armed with weapons of mass destruction. However, numerous types of ballistic and cruise missiles have achieved dramatic improvements in accuracy that allow them to be used effectively with conventional warheads."

The report comes as President Donald Trump's administration seeks a way to halt North Korea's drive to develop a nuclear-armed intercontinental ballistic missile that could hit the U.S. mainland. While citing the ballistic missile programs being pursued by Kim Jong Un's regime in Pyongyang and by Iran, the study describes a broader proliferation of missiles, advanced technology and launch options.