The United States ambassador to the United Nations, Nikki Haley, was not mincing words when she stepped up at the UN Security Council.
The emergency meeting in New York was called to deal with North Korea's watershed test of an intercontinental ballistic missile.
Leader Kim Jong-un has provocatively dubbed the launch a "gift" for the United States as it celebrated its independence day.
Ms Haley says all nations are at threat, not just the United States and its allies, which include Australia.
"I must say that today is a dark day. It is a dark day because yesterday's action by North Korea made the world a more dangerous place. Their illegal missile launch was not only dangerous, but reckless and irresponsible. It showed that North Korea does not want to be part of a peaceful world."
And Ms Haley warned of potential retaliation.
"The United States is prepared to use the full range of our capabilities to defend ourselves and our allies. One of our capabilities lies with our considerable military forces. We will use them if we must."
The US representative says she spoke with President Donald Trump earlier in the day about using trade restrictions to target countries that continue to deal with North Korea.
That was seemingly a reference to China, North Korea's only major ally and its biggest trading partner.
"There are countries that are allowing, even encouraging, trade with North Korea in violation of UN Security Council resolutions. Such countries would also like to continue their trade arrangements with the United States. That's not going to happen."
Nikki Haley flagged a fresh Security Council resolution which she says will be a proportionate response to the North Korean threat.
That could include restricting the flow of oil to its military and weapons programs.
Hours earlier, Mr Trump expressed his frustration over China and its trade program with North Korea, writing on Twitter, "So much for China working with us."
But Russia's foreign minister, Sergei Lavrov, has warned against escalating action.
"It's perfectly clear to Russia and China that any attempts to justify the use of force by referring to Security Council resolutions are unacceptable and will lead to unpredictable consequences in this region, which borders both the Russian Federation and the People's Republic of China."
Australia's acting prime minister, Barnaby Joyce, says the Government symphathises with the United States on any potential trade action against China.
"If people want to aid and abet that threat of the North Korean leadership, then ... well, obviously, we can't be supporting them."
Speaking to the ABC, Mr Joyce has played down the economic impact such action would have on Australia.
He says the greater economic threat would be if North Korea were not stopped.
"The trade sanctions, the effect of trade sanctions, would pale into insignificance against what would happen if North Korea continues down this path, because, if North Korea was to actually make a mistake in one of their launches -- that's all they have to do, they don't have to deliver a weapon, they just have to make a mistake and drop one of their missiles, you know, I imagine, into South Korea or onto Japan -- then the economic plan for China, the economic plan for South-East Asia, would cease that moment. It would be devastating for global economics and absolutely devastating for Chinese economics."
