The United States, Japan and South Korea on Sunday condemned North Korea's recent nuclear tests.
U.S. Secretary of State John Kerry met with the foreign ministers of Japan and South Korea on the sidelines of the U.N. General Assembly, calling for tough measures to isolate North Korea after its nuclear test earlier this month.
North Korea had been widely criticized for its nuclear tests and ballistic missile launches.
Kerry said the U.S. and the other two countries would "make it clear to a reckless dictator that all he is doing through his actions is isolating his country, isolating his people and depriving his people of genuine economic opportunity."
South Korea's foreign minister, Yun Byung-se, called North Korea's testing a "ticking time bomb," warning that the country poses a threat to the entire world.
Earlier this month, the Obama administration condemned North Korea's second nuclear testing this year.
The Obama administration has also been pushing for Japan and South Korea to set aside their differences and work together as North Korea's threat to security in the region intensifies.
"We must make North Korea understand that repeated provocations will isolate them from the international community and that there can be no bright future for them at all," Japanese Foreign Minister Fumio Kishida said.
In a joint statement, all three governments said they are "exploring ways to work together."
The Associated Press contributed to this report.