SEOUL, Feb. 5 (Yonhap) -- South Korea and the United States have been exchanging opinions on new possible U.N. sanctions against North Korea in case it conducts a third nuclear test, government sources here said Tuesday.

Pyongyang has vowed to detonate nuclear devices in response to the U.N. Security Council resolution last month tightening sanctions against it as punishment for its Dec. 12 rocket launch, with a series of signs indicating that the North has completed preparations to conduct the test at any time. It had previously carried out the tests in 2006 and 2009.