It's interesting to view through the lense of 'new media' vs 'broadcast media'.
In the old broadcast media days, US kept a pretty close eye on foreign media networks and they never had a foothold the way American media companies had. Think RT
Meanwhile, VOA operated (still does) around the globe spreading freedom and liberty. (Not sarcasm, really...)
Today, we have foreign media operators serving content to the American population, including minors, unfettered.
Look at the disasters of the 20th century for evidence of the power of ideas. A group of people united by an idea is a force to reckon with, and we're allowing foreign agents to control the flow of ideas on a broad scale. (I'm not against free speech, quite the opposite, I'm just pointing out the obvious).
These questions aren't simple to answer, nor are the proposed solutions going to make people happy, but you've rightly identified they're of pressing national concern.
One thing is for certain: we're in for the time of our lives.