North Korea has slammed US President Donald Trump's "Golden Dome" missile shield plan as a "very dangerous" threat that aims to weaponise space, the country's media reported on Tuesday.

Pyongyang's foreign ministry has issued a memorandum calling the system "a very dangerous 'threatening initiative' aimed at threatening the strategic security of the nuclear weapons states," the Korean Central News Agency (KCNA) said.

Trump announced new details and initial funding for the missile shield system last week, calling it "very important for the success and even survival of our country".

The initiative faces significant technical and political challenges, according to analysts, and could come at a hefty price tag.

The memorandum by nuclear-armed North Korea accused the United States of being "hell-bent on the moves to militarise outer space," KCNA said.

"The US plan for building a new missile defence system is the root cause of sparking off global nuclear and space arms race by stimulating the security concerns of nuclear weapons states and turning the outer space into a potential nuclear war field," it added.

Washington - Seoul's key security ally - has in recent years ramped up joint military exercises and increased the presence of strategic US assets, such as an aircraft carrier and a nuclear-powered submarine, in the region to deter the North.

Pyongyang has repeatedly declared itself an "irreversible" nuclear weapons state and routinely denounces joint US-South Korea drills as rehearsals for invasion.

China has similarly expressed strong concerns about Washington's Golden Dome plan, accusing the United States of undermining global stability.

The plan's Golden Dome name stems from Israel's Iron Dome air defence system which has intercepted thousands of short-range rockets and other projectiles since it went into operation in 2011. (AFP)