President Trump recently said he would impose a 25% tariff on steel imports and a 10% tariff on non-US aluminium.
Predictably, this has gone down rather badly in the European Union, which has responded by threatening new taxes on US-made goods.
For Harley Davidson, any new European taxes could add significant pressure at a time when the manufacturer is already struggling.
Europe remains the biggest market for Harleys outside the US. 39,773 motorbikes were sold in Europe last year, equating to 16% of worldwide sales. In terms of non-US sales, the European market equates to a huge 42%.
Any new taxes could seriously damage the company's growth in Europe. The impact could be even worse if other countries decide to engage in tit-for-tat tax hikes.
Harley Davidson may be tempted to open new manufacturing facilities overseas in order to avoid tariffs. The firm has already opened a facility in India, thereby bypassing the nation's up-to-100% import duty on motorcycles.
The firm also plans to build a plant in Thailand, enabling it to side-step 60% import tariffs - and build machines for much less, potentially further opening up the Asian market.
But replicating such a manoeuvre in Europe would take time and money. European-made bikes would also be far costlier to build than somewhere like Thailand.
If the US administration triggers a tit-for-tat trade war, there's little doubt Harley Davidson would struggle. Time will tell if one of America's greatest exports falls foul of policies designed, ironically, to protect the US economy.