That being said, Kim Jong is deranged and would not leave US citizens out of the war. The US would ensure the safety of Korean civilians. That is the only advantage NK would have over the US. The US has a much stronger and larger military... Plus we have many more allies.
North Korea would not win a war against the United States. They would get destroyed and it would not be fair. The United States has the strongest military in the world and we have shown in the past that we have no problem going all in on a war against another country.
North Korea probably couldn't beat the south with conventional weapons, let alone the US, but if it goes nuclear, well, let's be honest, they have 5-10 nukes that can cause serious damage to Japan, maybe destroy South Korea and the US bases on it, but then the US will respond in kind and North Korea will cease to exist, so no, the North stands no chance, unless China decides to help out, in which case we are all going to die.
No fuel means soldiers have to walk and leave heavy armament behind, tanks can't move and jets can't fly. By the time the North Korean soldiers get anywhere they'd be tired. Also how would North Korea feed its soldiers in the front lines it has no logistics? USA would win hands down.
I do not think that the North Koreans have any chance of defeating the United States in a war. We simply have too large of a military with superior technology. We could sit back with drones and pick apart North Korea while they sit there and have no idea what to do.
There is very little possibility that North Korea could win in a war against the United States. North Korea's army is a relic from the Cold War. It has completely outdated technology and crumbling infrastructure. The United States military outperforms the Korean military in every single test you can think of.