Updated February 24, 2017 08:41:57

Photo: Among Donald Trump's plans for big business is an overhaul of the tax system. (AP: Evan Vucci)

US President Donald Trump says he wants to build up the US nuclear arsenal to ensure it is at the "top of the pack", saying the United States has fallen behind in its atomic weapons capacity.

Mr Trump also said China could solve the national security challenge posed by North Korea "very easily if they want to", ratcheting up pressure on Beijing to exert more influence to rein in Pyongyang's increasingly bellicose actions.

In his first comments about the US nuclear arsenal since taking office on January 20, Mr Trump said the United States had "fallen behind on nuclear weapon capacity".

"I am the first one that would like to see nobody have nukes, but we're never going to fall behind any country even if it's a friendly country, we're never going to fall behind on nuclear power," he said.

"It would be wonderful, a dream would be that no country would have nukes, but if countries are going to have nukes, we're going to be at the top of the pack."

The new strategic arms limitation treaty, known as New START, between the US and Russia requires that by February 5, 2018, both countries must limit their arsenals of strategic nuclear weapons to equal levels for 10 years.

The treaty permits both countries to have no more than 800 deployed and non-deployed land-based ballistic missile launchers and heavy bombers equipped to carry nuclear weapons, and contains equal limits on other nuclear weapons.

Analysts have questioned whether Mr Trump wants to abrogate New START or would begin deploying other warheads.

In the interview, Mr Trump called New START "a one-sided deal".

"Just another bad deal that the country made, whether it's START, whether it's the Iran deal ... we're going to start making good deals," he said.

The United States is in the midst of a $US1 trillion, 30-year modernisation of its aging ballistic missile submarines, bombers and land-based missiles, a price tag most experts say the country cannot afford.

Trump angry at Russia, North Korea

Mr Trump also complained the Russian deployment of a ground-based cruise missile was in violation of a 1987 treaty that banned land-based American and Russian intermediate-range missiles.

"To me it's a big deal," Mr Trump said.

Asked if he would raise the issue with Russian President Vladimir Putin, Mr Trump said he would do so "if and when we meet". He said he had no meetings scheduled as of yet with Mr Putin.

Speaking from the Oval Office, Mr Trump declared "we're very angry" at North Korea's ballistic missile tests and said accelerating a missile defence system for US allies Japan and South Korea was among many options available.

"There's talks of a lot more than that," Mr Trump said, when asked about the missile defence system.

"We'll see what happens. But it's a very dangerous situation, and China can end it very quickly in my opinion."

Reuters

Topics: donald-trump, world-politics, us-elections, united-states

First posted February 24, 2017 08:36:07