Donald Trump was elected on a promise to tear up trade agreements and impose tariffs and quotas on countries - like China and Mexico - who he claimed were exploiting trade rules in a way that was costing American jobs.
Earlier this week America imposed tariffs on washing machines and solar panels that are manufactured in China.
In Davos on Wednesday, Wilbur Ross - the US Commerce Secretary - told journalists that “US troops are now coming to the ramparts” in the fight against “predatory trade practices”.
On Friday, President Trump told participants at the World Economic Forum that the United States was committed to “fair” and “reciprocal” trade but repeated his threat to take action against countries who “exploit the system at the expense of others”.
- Joel Hills explains that the outcome of the Bombardier case shows the limitations of Donald Trump's "America first" policy.
The dispute between Boeing and Bombardier was initially a commercial dispute but it quickly became political. In December, Wilbur Ross, held Bombardier up as an example unfair state aid.
The British and Canadian governments argued the case was unjustified and urged the White House to intervene.
Theresa May raised the issue with Mr Trump every time they met - she did so again on Thursday - but to no avail.
The British government expected to lose this case and were preparing for job losses in Belfast.
The US International Trade Commission’s ruling tells us something about the limits of President Trump’s reach.
His policy of “America First” is not just bravado.
Trump believes in it and knows it plays well at home.
But although President Trump is powerful, America is a democracy and there are checks and balances on his power.
He can’t do what he wants.