Declassified documents published on Friday show that the United States believed its military and South Korea’s forces would “undoubtedly win” a conflict on the divided Korean peninsula, during a 1994 standoff over Pyongyang’s nuclear ambitions.



But long before North Korea had developed nuclear weapons, the Pentagon estimated that some 490,000 South Korean service members and 52,000 US personnel would be killed or wounded in the first three months of any conflict.

The assessment does not mention North Korean and civilian casualties, but analysts say losses would be enormous.

Today, with North Korea almost able to directly threaten the US mainland with nuclear strikes, the possibility of conflict looms as it did in 1994.

At that time, President Bill Clinton’s administration considered a cruise missile strike on a North Korean nuclear complex after it began defuelling a reactor that could provide fissile material for bombs for the first time. Former president Jimmy Carter headed off a conflict, meeting with the founding North Korean leader, Kim Il-sung, and helping seal an aid-for-disarmament agreement. The pact endured for nearly a decade, despite frequent disputes and periodic flare-ups on the peninsula.

“We had taken a very strong position that we would not permit North Korea to make a nuclear bomb,” William Perry, who was defense secretary during the crisis, said this week. “We have said that many times since then, but then we really meant it.”

A declassified transcript published by the National Security Archive at George Washington University records Perry’s discussion on the standoff with South Korea’s president in 1998. Perry was by then Clinton’s special envoy for North Korea.

Q&A Why does the North Korean regime pursue a nuclear programme? Show Much of the regime’s domestic legitimacy rests on portraying the country as under constant threat from the US and its regional allies, South Korea and Japan.

To support the claim that it is in Washington’s crosshairs, North Korea cites the tens of thousands of US troops lined up along the southern side of the demilitarised zone – the heavily fortified border dividing the Korean peninsula. Faced with what it says are US provocations, North Korea says it has as much right as any other state to develop a nuclear deterrent. North Korea’s leader Kim Jong-un is also aware of the fate of other dictators who lack nuclear weapons.

Perry told the then president, Kim Dae-jung, that the US had planned for a military confrontation and that “with the combined forces of the ROK and US, we can undoubtedly win the war”. ROK refers to the abbreviation of the South’s official name, the Republic of Korea.

Speaking to South Korea’s Kim, who pursued a “sunshine” policy of diplomatic outreach to North Korea, Perry said the “war involves many casualties in the process. As a former defense secretary, I am well aware of the negative aspects of war, and will do my best to avoid war.”

Since then, North Korea has made dramatic advances in its nuclear and missile development, particularly under its current young leader, Kim Jong-un. Last month, it tested an intercontinental ballistic missile with a likely range of more than 8,000 miles (13,000km), moving it closer to perfecting a nuclear-tipped projectile that can strike all corners of the US mainland.

Trump has not ruled out using force to stop the North from achieving that capability if diplomacy fails. The US has stepped up its military drills with allies, which Pyongyang condemns as preparations for invasion. This week, the US and South Korea held air force drills involving more than 200 aircraft, including six US F-22 and 18 F-35 stealth fighters.

North Korea’s foreign ministry warned this week: “The remaining question now is: when will the war break out.”

Speaking at an Arms Control Association briefing in Washington, Perry urged a renewed effort at diplomacy, which he said would not get North Korea to give up its nukes in short order, but could lower the likelihood of war.

He said that a nuclear-armed North Korea would not attack America but may be emboldened in military provocations against South Korea that could spiral into a wider conflict. The US could itself blunder into a nuclear war if it undertook a conventional military strike on North Korea that prompted the North to attack the South, he said.

“An all-out war with North Korea, nuclear war, even if China and Russia did not enter,” Perry said, “could still entail casualties approximating those of World War I or even World War II.”