The United States has said "all options are on the table" to deal with North Korea.
US Ambassador to the United Nations Nikki Haley also denounced North Korean leader Kim Jong-un after the United Nations Security Council discussed Pyongyang's launch of four ballistic missiles on Monday.
"We are not dealing with a rational person," said Haley. "It is an unbelievable, irresponsible arrogance that we are seeing coming out of Kim Jong-un at this time."
She said the administration of US President Donald Trump was re-evaluating how it would handle North Korea and that "all options were on the table.
"We are making those decisions now and we will act accordingly," Haley said.
North Korea fired the missiles into the sea off Japan's coast in response to the annual US-South Korea military drills, which Pyongyang sees as preparation for war.
According to the Kyodo News Agency, one of the missiles fell "closer than ever before" from the Japanese coast, around 200km northwest of the country's Noto Peninsula.
Al Jazeera's Mike Hanna, reporting from the UN headquarters in New York, said "it doesn't appear there was that much movement" in the closed-door Security Council emergency meeting called by the US, Japan and South Korea.
"All parties came out and insisted that the sanctions already in place against North Korea must be fully enforced, the argument being that there is still some leeway with the enforcement of these sanctions," he said.
Pyongyang has fired dozens of missiles and conducted two of its five nuclear tests in the past year in defiance of UN resolutions.
Chinese Foreign Minister Wang Yi said on Wednesday the tests by the North and the joint drills across the border in South Korea were causing tension to increase like two "accelerating trains coming toward each other". He suggested a "dual suspension" to allow all sides to return to negotiations.
"We have to see some sort of positive action taken by North Korea before we can ever take them seriously," Haley said when asked about Beijing's proposal.
She said the drills had been held annually for 40 years and North Korea was always notified.
The US military on Tuesday started to deploy the first elements of its Terminal High Altitude Area Defense (THAAD) anti-missile system to South Korea, which China opposes.
Diplomats said China raised the THAAD deployment during Wednesday's closed-door UN meeting.
North Korea's foreign ministry spokesman categorically rejected a Security Council statement that labelled what he called its "routine" ballistic missile a threat.
The spokesman reiterated that the US-South Korean exercises are pushing the situation "to the brink of a nuclear war" and the North was responding with "the self-defensive right of a sovereign state".
Source: Al Jazeera and news agencies