White House national security adviser HR McMaster said Saturday that North Korea represents "the greatest immediate threat to the United States" and that the potential for war with the communist nation is growing each day.
McMaster said the possibility of war with the North was "increasing every day".
"We are in a race to be able to solve this problem", Mr McMaster said.
"There are ways to address this problem short of armed conflict, but it is a race because he's getting closer and closer, and there's not much time left".
The photos appeared to show the missile with at least two large nozzles on its first stage, instead of the one large and several smaller nozzles on the Hwasong-14.
The country's state media announced the test on Wednesday, hours after leader Kim Jong Un ordered the launch of the Hwasong-15 missile, which reached the highest altitude ever recorded by a North Korean missile.
At the end of November the USA unveiled fresh sanctions against the North, which it said were created to stop its funding of nuclear and ballistic missile programmes.
South Korea US kick off air drills
It comes days after the North fired a new intercontinental ballistic missile (ICBM) and elevated tensions in the region.
North Korea has repeatedly rejected accusations of human rights abuses and blames sanctions for a dire humanitarian situation.
U.S. Air Force aircraft arrived in South Korea on Saturday to participate in a joint aerial drill just a week after North Korea launched a ballistic missile.
After the missile was tested, Trump tweeted Wednesday that "additional major sanctions will be imposed on North Korea".
"What matters is the fact that the drill simulating an actual war is to be staged at a time when insane President Trump is running wild", a commentary carried by the official Korean Central News Agency said. The other was the "testing of a long-range ICBM", the implication being this had been achieved with the most recent launch.
United Nations Security Council ministers will meet on December 15 to discuss North Korea's nuclear and missiles programs and the body will also meet separately this month to discuss human rights abuses in the North Asian country, an annual meeting that its ally China has tried to prevent for the past three years. A minimum of nine votes are needed to win such a vote and China, Russia, the United States, Britain and France can not wield their vetoes.
Democrats could come up losers in government shutdown fight
The White House press secretary, Sarah Sanders, said the meeting would proceed as scheduled with McConnell and Ryan. Democrats thus have a surprising amount of leverage on the contents of the year-end spending bill.