North Korea has informed it has successfully tested an engine designed for an intercontinental ballistic missile, BBC reports.
The new type of engine would "guarantee" the capacity to launch a nuclear strike on the US mainland, the KCNA news agency said.
The test was carried out at the country's long-range missile launch site near its west coast. The performed tests comes as the latest in a series of launches conducted by the isolated nation.
Leader Kim Jong-un oversaw the test, state media reported, during which "the engine spewed out huge flames with a deafening boom".
The country would now be able to "keep any cesspool of evils in the earth including the US mainland within our striking range," Mr Kim was quoted as saying.
North Korea should "refrain from actions and rhetoric that further destabilise the region and focus instead on taking concrete steps toward fulfilling its commitments and international obligations," said Mark Toner, a US State Department spokesman.
In March, Pyongyang said it had developed nuclear warheads that were small enough to be integrated on ballistic missiles.
However, experts doubt the clams.
Also in March, North Korea threatened with "indiscriminate" nuclear strikes on the United States and its southern neighbor, as the two countries held large-scale joint military drills, which are considered by the North as a rehearsal for a possible invasion.
Meanwhile, Washington has imposed new sanctions on North Korea after a nuclear test was conducted in January and a satellite was launched in February, which was widely seen as a test of banned missile technology.
The US has also held talks with South Korea aimed at deploying an American missile defense system to the Korean peninsula, a move strongly opposed by North Korea, Russia and China.
Beijing says the Thaad anti-missile system compromises its security and would undermine its nuclear deterrent.