After three years spent trying to deter Russia from destroying Ukraine, European Union leaders grappled on Monday with how to respond to a major ally who appears determined to start a trade war or even seize part of their territory.

Shares in Europe and Asia have fallen after US President Donald Trump announced tariffs on Canada, Mexico and China, and said tariffs on the EU would "definitely happen". The German and French stock markets were down about 2%, with shares in carmakers among the worst hit, while London's FTSE 100 dropped more 1%.

Costco customers are waiting in long lines and panic-buying eggs because of Trump’s new tariffs on imported goods. That’s on top of an already short supply of eggs due to an outbreak of avian flu. The current egg situation in America is anything but over-easy.

Amid warnings of price increases, Canada moved quickly to retaliate, China said it had planned countermeasures and Mexico said it would soon unveil its response.

On Friday afternoon, around the same time a delegation of senior Canadian officials was preparing to meet with President Donald’s Trump’s border czar in a bid to stave off withering new tariffs, Trump himself essentially told them from afar: Don’t bother.

European leaders are asserting that President Donald Trump’s proposed tariffs against the European Union will force member states to fight back until the United States respects their economic power. White House officials announced earlier this week that a slew of heavy tariffs would be implemented against the EU,