US President Donald Trump has warned that North Korea is threatening the lives of Americans with its nuclear, chemical and biological weapons, and promised that these threats will be "taken care of".

As the American leader unveiled the first national security strategy of his administration on Monday (18 December), he underscored the rising threats from nations such as North Korea and Iran, which are ruled by what he called as rogue governments.

The 68-page policy document, a blueprint for the US' national security under the "America First" plan, read, "North Korea seeks the capability to kill millions of Americans with nuclear weapons."

It went on: "North Korea is also pursuing chemical and biological weapons which could also be delivered by missile."

The four key elements of the policy document were protecting the American homeland, promoting the US' prosperity, preserving peace through strength and expanding the American influence globally.

Trump's vision report, which was put together by his officials in the past 11 months, continued, "We remain ready to respond with overwhelming force to North Korean aggression and will improve options to compel denuclearisation of the peninsula."

Explaining the strategy during a campaign-like address from the Ronald Reagan Building, Trump said his administration is leading a diplomatic offensive to exert "maximum pressure" on reclusive North Korea. He added more measures are needed as part of the "toughest-ever sanctions".

"America and its allies will take all necessary steps to achieve a denuclearisation and ensure that this regime cannot threaten the world," said Trump. "Situation should have been taken care of long before I got into office when it was much easier to handle. But it will be taken care of. We have no choice."

Trump's policy document also revealed that the US is readying a layered missile defence system — capable of countering the missile threats even before its launch — particularly to combat challenges posed by Iran and North Korea.

"America is in the game, and America is going to win," Trump told the gathering, which included his cabinet members and military officers.

In the new security plan, the Trump administration also hit out at Russia and China, labelling them as "competition" and "rival powers" which could potentially harm the US' security. The emboldened China and Russia seek to "challenge American power, influence, and interests" and attempt "to erode American security and prosperity", he reportedly said.

Trump, however, added that his administration should make attempts in sealing a "great partnership with them".

Donald Trump and North Korea
President Donald Trump pledges the threats from North Korea will be "taken care of" Reuters