US Democrats are warning Republican President Donald Trump of any pre-emptive attack on North Korea

This undated picture released by North Korea's official Korean Central News Agency (KCNA) on May 22, 2017 shows North Korean leader Kim Jong-Un (C) inspecting the test-fire of a ground-to-ground medium-to-long range strategic ballistic missile Pukguksong-2. (Photo by AFP)

US Democrats are warning Republican President Donald Trump not to launch an attack against North Korea.

A group of 64 Democrats concerned with breakout of war with the nuclear power said in a letter Tuesday that any preemptive attack should be approved by US Congress ahead of being operationalized, The New York Times reported.

“Few decisions are more needing of debate than a move to launch attacks, or declare war, on a nuclear-armed state such as North Korea,” read the letter. "In such a volatile region, an inconsistent or unpredictable policy runs the risk of unimaginable conflict.”

They also asked the Trump administration to present evidence of a policy aimed at boosting prospects of negotiations with Pyongyang.

“We respectfully request more information about the steps your administration is taking to advance the prospects or direct negotiations that could lower the potential for catastrophic war and ultimately lead to the de-nuclearization of the peninsula.”

US President Donald Trump (R) and First Lady Melania Trump wave goodbye as they board Air Force One at Ben Gurion International Airport in Tel Aviv, prior to their departure for Rome on May 23, 2017.  (Photo by AFP)

Tensions have been running high in the region over North Korea’s nuclear and missile programs, which Pyongyang sees as a deterrent against a potential invasion by its adversaries.

In the letter, the Democrats argued that all previous administrations have ruled out the possibility of military action against the country.

“[They] ultimately determined there was no military option that would not run the unacceptable risk of counterreaction from Pyongyang,” read the letter.

North Korea recently test-fired a new ballistic missile dubbed Pukguksong-2, drawing condemnation from the UN Security Council.

Last month, the US sent a naval strike group into the West Pacific near the Korean Peninsula to threaten Pyongyang.