Lieutenant General Jan-Marc Jouas has warned that troops in South Korea will be "outnumbered" if war was to suddenly break out
A former deputy commander in the US Army has warned that America will not win in a war against North Korea.
It's estimated that the secretive state has around 1.2 million troops at its disposal - which is a substantially higher number than the 28,500 US military personnel currently stationed in South Korea.
It would mean that US troops would be dangerously "outnumbered" should war suddenly break out.
Lieutenant General Jan-Marc Jouas, a former deputy commander of US Forces in Korea, sent his warning in a letter addressed to Representatives Ted Lieu and Ruben Gallego and Senator Tammy Duckworth.
All three have previously expressed concern over the rhetoric Donald Trump has used when it comes to North Korea and Kim Jong-un.
In a letter, obtained by Newsweek, Jouas said: "The 28,500 U.S. Armed Forces personnel in South Korea are vastly outnumbered by North Korean forces, as well as [South Korean] forces that will conduct the overwhelming majority of the fighting.
"Unlike every conflict since the last Korean War, we will not be able to build up our forces prior to the start of hostilities."
Over the weekend, Trump appeared to use Twitter like his own personal diary, sending another flurry of insults to Kim Jong Un.
The President of the United States and Leader of the Free World tweeted complaining that the North Korean despot had been mean to him by calling him "old".
And he added that he would never call Kim "short and fat."
Trump made the comment on Twitter Sunday morning after attending the Asia-Pacific Economic Cooperation (APEC) summit in Vietnam.
Trump tweeted: "Why would Kim Jong-un insult me by calling me 'old,' when I would NEVER call him 'short and fat?'
"Oh well, I try so hard to be his friend - and maybe someday that will happen!"
Trump has traded insults and threats with the North Korean leader in the past amid escalating tensions over Pyongyang's nuclear and missile programs.
While Trump has referred to the North Korean leader as "rocket man", Kim Jong-Un has previously called the US President a "mentally deranged US dotard".
Trump's latest tweet is most likely in response to a North Korean state news agency statement shared earlier this week as he headed to South Korea as part of his five-country Asia tour.
"No one can predict when the lunatic old man of the White House, lost to senses, will start a nuclear war against [North Korea],” it said.
"The US should not expect us to make any change."