The South Korean military said on Wednesday that North Korea fired an unspecified bullet in sea off the east coast.
For its part, the coast guard in Japan said North Korea has launched what may be a ballistic missile.
Since the beginning of the year, Pyongyang has led more than ten test missiles, including the launch of an ICBM, in a precedent from 2017.
Earlier, Linda Thomas Greenfield, the US Ambassador to the United Nations, said the US would like the Security Council to vote this May to impose more sanctions on North Korea.
Last month the United States distributed a draft resolution to the 15-member Security Council proposing a tobacco ban, halving oil exports to North Korea and blacklisting the Lazarus hacker group.
However, Russia and China have already expressed their opposition to tougher sanctions in response to Pyongyang’s March launch of an ICBM, the first since 2017.
The Security Council resolution needs nine “yes” votes to pass if no veto is used by any of the Council’s five permanent members; Russia, China, France, Great Britain and the United States.