If I was a foreign power I wouldn't go up militarily against the US, that would be disastrous. Instead, I would head to the universities, I would fund the companies that are in close proximity to the consumer of popular media. I would start 20,30,40 years ago and slowly change what the people in your country thinks about their status quo. The top brass doesn't care because they don't see weapons. Underpaid, underappreciated, unscrupulous individuals are easily won over. Again, the decision makers don't see the enemies here. Then one day, the small cuts collectively add up and the wounds begin to rot from within. Once again, nobody raises alarms because they are incentivized or naivete from being #1 for so long.
I would go even further by focusing on the existential crisis of the non-majority ethnic groups and exploit it into hating the very country they are in because of isms. Then you go to the other side which is the conservative portion of the majority ruling class and sell them the idea that those people are ungrateful and hostile.
Throw technology and fast food equivalent of entertainment that creates a population addicted to the short bursts of serotonin and you just might be witnessing what you are seeing today.
Bonus points for dividing the political ruling class by feeding exploitative information true or not that will be weaponized.