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 they don't carry nuclear warheads, according to a new Pentagon report.

"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 stop 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.

"Ballistic missiles can be deployed in silos, on submarines, surface ships, road- and rail-mobile launchers and aircraft," the report said. "Mobile missiles can provide greater pre-launch survivability. The last decade has seen a dramatic increase in ballistic missile capabilities to include accuracy, post-boost maneuverability, and combat effectiveness."

Among the new technologies are hypersonic glide vehicles being developed by Russia and China.

"HGVS are maneuverable vehicles that travel at hypersonic (greater than Mach 5) speed and spend most of their flight at much lower altitudes than a typical ballistic missile," according to the report. "The combination of high speed, maneuverability, and relatively low altitude makes them challenging targets for missile defense systems."

Other findings in the report by the National Air and Space Intelligence Center and the Defense Intelligence Ballistic Missile Analysis Committee: