Nuclear War and Chemical War. You never said a country but this would have to be Russia and North Korea in my opinion, which you cannot forget. China has good relations with us. You said enemies and to be honest those 2 countries are the number 1 most likely to cause trouble down the road. North Korea now has a missile that can reach the East Coast and actually make land fall.
China has capabilities beyond that but they are in good terms with the United States. I remember something happening before with China boats and ships but that's nothing to be too concerned with. They are apart of the United Nations Pact which has yet to be messed with on grounds of where it would be removed.
My uncle is actually from Chile @Laifot which is in the same continent as Paraguay. I'm not related to him. He's my aunts husband but he's told me stories about how tough South America can be for fights and stuff. Not sure if Paraguay is any different than Chile. But burning anyone's countries flag is basically one of the worst things you can do.
Iran is afraid of us. North Korea isn't as much so fearful of the United States as they should be. Like I said before, their nukes could reach us by way of the ocean.
To be honest, guess how no one blows any off ever? Because each nuclear bomb has what they call a nuclear launch code sequence that the US government has control over. They have every single one from every single country. That's what's mainly been keeping us safe. This is thanks to some of the best United States hackers known to man. Some people that were sentenced to life got released to work for the US in hacking. They call these people "White Knights". They are incredible at what they do. But there is a certain class of bomb that has a sequence. The ones North Korea is using are called guided missiles and there are no sequences for them. The kind like Hydrogen and Atomic type weapons all have a code sequence. @Laifot I bet you might be interested in this. I bet you didn't know that