American intelligence agencies initially believed that North Korea was still years away from developing a missile that could reach the United States - but may have gotten their predictions wrong, a new report claims.

When President Donald Trump first took office almost a year ago, intelligence agencies told the new administration that they had at least four years to come up with a plan to slow or stop North Korea's development of an atomic bomb that was capable of striking US soil, the New York Times reports.

Agency officials believed the East Asia country's leader Kim Jong un faced a wide range of issues that would give Trump and his administration more than enough time to negotiate or look into countermeasures.

The ICBM Hwasong-15 was launched in Pyongyang, North Korea in November. It's said the missile, pictured, can fly more than 8,000 miles and reach Washington

The Hwasong-15, pictured, did not survive re-entry into the Earth's atmosphere and broke apart in the waters off the coast of Japan, US officials said

President Donald Trump (left) said he would talk on the phone with North Korean leader Kim Jong un but not without preconditions

The intelligence community also said 33-year-old Kim was 'young, inexperienced and distrusted by his military', according to the outlet.

However, when senior officials began looking more heavily into North Korea's weapons programs, they made two wrong assumptions about how fast the country was working to develop stronger and deadlier warhead.

One wrong assumption, the Times claims, is that officials thought North Korea would need as much time to solve the rocket science as other countries did during the Cold War. Officials also misjudged Kim, who made the country's weapons program a higher priority than his father or grandfather.

One official reportedly thought the North Korean leader wouldn't be able to strike the US until 2020 or 2022.

Lt. Gen. H.R. McMaster, Trump's national security adviser, acknowledged in an interview with the Times on Saturday that Kim's weapons programs development 'has been quicker and the time timeline is a lot more compressed than most people believed'.

'We have to do everything we are doing with a greater degree of urgency, and we have to accelerate our own efforts to resolve the issue short of conflict, he continued.

A spokesman for the director of national intelligence, however, told the outlet that the intelligence community was not caught off guard with the leader's accelerated pace.

'Any suggestion that we didn't see these tests coming is dead wrong,' Brian P. Hale said. 'The intelligence community has always assessed that Kim Jong un is firmly committed to developing a nuclear capability. We were, therefore, no surprised by his accelerated pace of testing over the past few years.'

Recently, Pyongyang staged eight intermediate-range missile tests, seven of which either blew up on the pad or shattered in flight.

Pyongyang staged eight t intermediate-range missile tests, including Hwasong-15 (pictured). Seven of the eight missiles either blew up on the pad or shattered in flight

Kim Jong un made North Korea's weapons programs a high priority when he became leader

Trump is said to be unaffected by the intelligence community underestimating North Korea and their weapons program

On November 29, North Korea launched its latest intercontinental ballistic missile (ICBM), dubbed Hwasong-15. It was said that the bomb could fly about 8,100 miles, which would reach Washington, but it did not survive re-entry into the Earth's atmosphere during the test.

US officials told Fox News that the missile broke apart landing in the waters close to the Japanese coast.

Despite the intelligence community's predictions seemingly being off, McMaster told the Times that President Trump is not worried.

'He doesn't have the expectation of perfect intelligence about everything. He is very comfortable with ambiguity,' he said. 'He understands human nature and understands he will never have perfect intelligence about capabilities and intentions.'

On Friday, Trump said he would be willing to talk to Kim on the phone but not with preconditions.

'Sure, I always believe in talking,' he told reporters while at a presidential retreat at Camp David, Maryland. 'Absolutely, I would do that.'