The US was "subsidizing" Europes social programs by taking up their slack on military spending.
That the US is subsidizing a country is not news. One of the biggest receivers of US tax payer money is Israel. Do you think Israelis would be living the lifestyle they live without US tax payer money? In fact, without US tax payer money buttressing their military, they may have already made a deal with the Palestinians! Where's the outrage at Israel receiving foreign aid? These same people that are ok with Israel receiving subsidizes are mortified at the though of poor kids receiving a subsidy (aka Pell grants) to go to college.
The US subsidizes anything and everything that it thinks will advance its interests. Those subsidies purchase a seat at the table. Foreign trade is one way that seat is purchased. We allow countries to impose tariffs on our products but don't impose tariffs on theirs. Why? Because it allows those countries to grow their economies and become stronger. They become dependent on the US and want to curry favor with us. They also serve as a bulwark against aggression by our enemies.
Trump's popularity suggests that buttressing our allies' economies at the expense of US workers has gone to far. However, the way Trump is going about it suggests that he is leveraging the frustration of American workers for a more nefarious purpose.
The emergency that Trump declared that gave him the authority to implement these tariffs can be rescinded by congress if only they hadn't ceded their authority to do so . That's right, republicans gave away congress's authority to put Trump in check. Why would they do that? It's obvious that they want to trash the US economy just as much as Trump does. That's is probably why they are not condemning Trump for chaos that he is causing.