The United States believes that North Korea may use biological weapons some day, which poses another major security threat on top of its nuclear weapons drive, according to an annual U.S. government report.

"The United States judges that North Korea may still consider the use of biological weapons as an option," the State Department said in its new report on international agreements and commitments to arms control, nonproliferation and disarmament.

North Korea became a state party to the Biological Weapons Convention (BWC) in 1987.

"North Korea continues to develop its biological research and development capabilities, but has yet to declare any relevant developments as part of the BWC confidence-building measures," the report read.

The department said North Korea's continued nuclear development, including its uranium enrichment activities and ongoing construction of a light-water reactor, violates U.N.

Security Council resolutions and the communist nation's own commitments under the 2005 deal with its nuclear negotiation partners -- South Korea, the U.S., China, Russia and Japan.

Pyongyang announced its withdrawal from the Nuclear Non-Proliferation Treaty (NPT) in January 2003.

Although North Korea conducted two nuclear tests in 2006 and 2009, respectively, and may prepare for a third one, it is unable to become a nuclear-weapons state as defined by the NPT, which limits that classification to five nations, the department said.

"We will not accept North Korea as a nuclear-weapon state," it said.

This year's report struck largely a similar tone on North Korea with the previous one.

A notable difference is the assessment of its suspected nuclear ties with Myanmar, also known as Burma.

In last year's report, the U.S. said it is on alert to any signs of Myanmar's nuclear weapons-related activities or intentions.

The U.S., however, said in the new version that "concerns that the United States expressed in last year's compliance report regarding Burma's interest in pursuing a nuclear program, including the possibility of cooperation with North Korea, were partially allayed."

The U.S. is apparently starting to gain some trust in Myanmar amid its nascent move towards democracy. (Yonhap News)