Donal O’Donovan: Plunging dollar tells it all – the US is heading for a crash and taking Ireland with it

Watch the dollar. It isn’t so much the canary in the coal mine as it is the tightening in the miner’s lungs. The greenback strengthened when Donald Trump imposed tariffs on Canada and Mexico.

That was based on a fairly run-of-the-mill calculation on the markets that the move would be inflationary in the US, limiting the scope for interest rate cuts there, but to a manageable if unpleasant extent..