If North Korea successfully launches its rocket, it would demonstrate that the North has the technological skills to send up a missile that could travel as far as the western United States. Washington and its allies also consider North Korea’s missile program an additional threat because the North has sold missile technology to the Middle East and is developing nuclear weapons that could potentially be loaded on its missiles.

After North Korea detonated its first nuclear device in 2006, the Security Council adopted a resolution banning North Korea from further nuclear and missile tests.

Washington warned that it would seek punishment at the Security Council  probably more sanctions on the already isolated country  if it goes ahead with the planned launch. And Japan has vowed to press for new sanctions if the rocket is tested.

But North Korea warned this week that further sanctions would cause it to quit the so-called six-party talks. The United States, South Korea, Japan, China and Russia have been trying for years to persuade North Korea to dismantle its nuclear weapons programs in return for economic aid.

The North’s defiance is the first major test for President Obama in dealing with Pyongyang.

“We intend to raise this violation of the Security Council resolution, if it goes forward, in the U.N.,” U.S. Secretary of State Hillary Rodham Clinton said Wednesday. “This provocative action in violation of the U.N. mandate will not go unnoticed, and there will be consequences.”