At the heart of President Donald Trump’s trade policy is currency. Today, he accused Japan and China of past currency devaluations. And his trade advisor, Peter Navarro, told the Financial Times that the euro is grossly undervalued, and that Germany is unfairly benefiting from it. But the idea that countries are actually manipulating their currencies can be really hard to pin down. And in some cases, it looks like the administration has put the pin down in the wrong spot.