Ukraine says it has never supplied defense technology to North Korea as tensions have increasingly ratcheted up between the North and the US in recent weeks.

Axar.az reports that the secretary of the Ukrainian Security and Defense Council, Oleksandr Turchynov, said on Monday that Kiev "has never supplied rocket engines or any kind of missile technology to North Korea."

In a statement published on their company's website, state-owned Ukrainian factory Yuzhmash also said that it had not produced military-grade ballistic missiles since independence from the Soviet Union in 1991.

"In the years of independence, Yuzhmash has not produced, and is not producing, missiles and military missile systems," the statement read.

The remarks came in response to an article in the New York Times that said North Korea may have purchased rocket engines from Ukraine, a close US ally.

Tensions over North Korea escalated in July, when Pyongyang twice successfully tested an intercontinental ballistic missile (ICBM) capable of targeting the US mainland.

US President Donald Trump said last week the US would rain "fire and fury" on North Korea, which some interpreted as threatening the country with a preemptive nuclear attack. A day later, he doubled down on his threat, saying a military option against North Korea is "locked and loaded."

In response to Trump’s dire warnings, North Korea said it was "carefully examining" a plan to strike the American Pacific territory of Guam with missiles. Guam is about 3,200 kilometers from Pyongyang, North Korea's capital.

The North Korean military said it could carry out a preemptive strike if there were signs of an American provocation.

Trump was criticized by both Democrats and Republicans for issuing a threat of launching a nuclear strike against North Korea with which the US has been in conflict since the start of the Korean War in 1950.

North Korea says it will not give up on its nuclear deterrence unless Washington ends its hostile policy toward Pyongyang and dissolves the US-led UN command in South Korea. Thousands of US soldiers are stationed in South Korea and Japan.