Japanese diplomats are meeting with Chinese and U.S. officials to try building a unified response to North Korea's missile launches earlier this week. In addition, Tokyo is asking Indonesia to intercede with Pyongyang.

A senior Japanese diplomat flew to China Friday to discuss how to confront North Korea over its missile program. In addition, the Japanese government is attempting to open a back-channel to North Korea via Indonesia.

Japanese officials say Prime Minister Junichiro Koizumi has asked the Indonesian president to carry a letter to North Korean leader Kim Jong Il.

President Susilo Bambang Yudhoyono is scheduled to visit Pyongyang later this month.

Japanese Foreign Ministry spokesman Tomohiko Taniguchi says the letter should make it clear to the North Korean leader that he is stepping over the line with his country's recent missile test-launches.

"A strong, powerful message should be relayed to North Korea to tell them that what they are doing is suicidal," he said.

On Wednesday, North Korea defied international warnings and expressions of concern by test firing seven missiles, all of which landed in the sea. The launches are seen by many countries, including the United States and Japan, as a provocation given Pyongyang's refusal to return to multilateral talks on ending its nuclear weapons programs.

On Saturday, Japanese officials will meet with U.S. Assistant Secretary of State Christopher Hill to discuss North Korea's missile launches and efforts to bring it back to nuclear disarmament talks. Hill on Friday visited China and South Korea for similar discussions.

Japan on Friday also brushed off Pyongyang's threat to take tough action unless Tokyo ends its sanctions against North Korea.

Taniguchi says North Korea should use the diplomatic route to voice complaints.

"If they are willing and ready to say the kind of things that they want to say to the press, why don't they come to us directly through the diplomatic channel?" he asked.

Tokyo is pushing the United Nations Security Council to adopt a resolution imposing sanctions on the reclusive communist state.

Japan hopes to convince China and Russia to cooperate on a resolution, a move the United States endorses. Beijing and Moscow, however, favor a less serious action.