Japan on Monday warned North Korea of "stern measures" if it launched a long-range missile, renewing the threat of economic sanctions.
"If North Korea test-launches missile, naturally Japan and the United States will take stern measures," said Chief Cabinet Secretary Shinzo Abe.
A series of reports have indicated North Korea is planning to test a long-range missile similar to the type that it fired over Japan in 1998.
Abe said the United States voiced concern to Pyongyang through its UN mission in New York on Saturday and that Japan did the same a day earlier via Beijing.
"There are no interests North Korea will achieve by launching a missile," Abe said.
The Japanese Parliament last week had approved a bill that would require sanctions -- such as banning port calls by North Korean ships and blocking remittance payments -- if the North does not make progress in a separate row over its abductions of Japanese civilians.
"As the bill allowing us to take unilateral action has been enacted, we will consider such measures if North Korea test-launches," Abe said.
Foreign Minister Taro Aso on Sunday also brandished the threat of sanctions, which are seen as hitting the impoverished regime hard by banning Pyongyang's ships and remittances by North Koreans in Japan.
Aso said Japan would consider a missile landing on its soil an "attack" and take the matter to the United Nations Security Council.