North Korea says a plan that could see it fire four missiles near the US territory of Guam will be ready in a matter of days.
State media said Hwasong-12 rockets would pass over Japan and land in the sea about 30km (17 miles) from Guam, if the plan was approved by Kim Jong-un.
It denounced Donald Trump's warnings of "fire and fury" and said the US leader was "bereft of reason".
The US has warned the North its actions could mean the "end of its regime".
US Secretary of Defense Jim Mattis said Pyongyang would be "grossly overmatched" in any war against the US and its allies.
There is a sense that the North Korean threat is rhetorical, as most people feel that if they really did strike with missiles it would be suicidal for the North Korean regime.
Separately, the European Union said it was freezing the assets of nine more people and four more entities, including North Korea's Foreign Trade Bank, in line with fresh sanctions approved by the UN Security Council on Saturday.
What is the North planning?
The North first announced on Wednesday that it had been drawing up plans for a missile strike against Guam, a Pacific island which is home to US military bases, strategic bombers and about 163,000 people.
A later statement carried by state media said the military would "finally complete the plan" by mid-August and send it to leader Kim Jong-un for his approval.
"The Hwasong-12 rockets to be launched by the KPA [Korean People's Army] will cross the sky above Shimane, Hiroshima and Koichi [Kochi] Prefectures of Japan," state news agency KCNA said, quoting army chief General Kim Rak Gyom.
"They will fly 3,356.7km for 1,065 seconds and hit the waters 30-40km away from Guam."
The Hwasong missiles are North Korea's domestically produced medium and long-range weapons.
