The US Secretary of State, Colin Powell, has confirmed reports that North Korea threatened last week to test a nuclear weapon.
But he has said that he is still hopeful that there will be further talks on de-nuclearising the Korean Peninsula.
The threat reportedly came during six-party talks held in Beijing last week to deal with North Korea's nuclear programme.
We will not be frightened
The discussions ended without resolution, but were not without drama.
Mr Powell has now confirmed that North Korea did say it intended to test a nuclear weapon.
Russian officials had denied this.
But speaking after a meeting with the South Korean foreign minister, Mr Powell said that whether such threats were interpreted as a statement or as a negotiating tactic, they would not change US policy.
"The way forward is not helped by threats and truculent statements that are designed to try to frighten the international community, or to try to frighten us," he said.
"We will not be frightened."
Although further talks have not yet been scheduled, Mr Powell said it remained possible that there could be another round of diplomacy.
But he cautioned that it would require the agreement of all six nations involved.