The bobbing and weaving that has made Donald Trump a capricious sparring partner for other world leaders has been on display ahead of the U.S. president’s trade talks today with European Commission President Jean-Claude Juncker.

Hours after tweeting that “tariffs are the greatest,” Trump said the U.S. and the European Union “should drop all tariffs, barriers and subsidies” before declaring “but they won’t!” (That, as Trump yesterday announced $12 billion in aid to U.S. farmers.)

Juncker and European Trade Commissioner Cecilia Malmstrom are set to present Trump with proposals aimed at staving off U.S. duties on European car imports amid signs that protectionism is slowly starting to weigh on the global economy.

The EU chief told a German television station his goal was to “calm down the overall situation” but that the EU was prepared to retaliate “immediately” if Trump moves ahead with the auto tariffs.

Underscoring how fraught the trans-Atlantic relationship has become, the last time Trump met Juncker he called the Luxembourger “a brutal killer.” Recounting the incident to Bavaria’s regional parliament, Juncker said he thought it had been meant as a compliment, “but I’m not so sure.”