Trump's tariffs: A negotiating tactic or the start of an 'economic nuclear winter'?

Traders called this morning a complete bloodbath as the UK's FTSE 100 joined world indexes in turning red as uncertainty over Donald Trump's tariffs continued to batter stock markets.

Across Asia and Europe, hundreds of billions have been wiped off companies' values, particularly in banking and manufacturing.

The cause is not just the imposition of those tariffs (the largest the US has inflicted since the 1930s) and the very obvious drag this will have on global trade and growth, but also the uncertainty of 'what next?'.

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Investors cannot work out if the Trump administration is genuinely wedded to tariffs on this scale, on the proviso that they will help re-shore companies and millions of jobs to the United States.

They don't know if they are permanent or merely part of a negotiating tactic to address trade imbalances, and for America to use its economic heft to strike better deals.

If Mr Trump is open to deals (the first test comes later in a meeting with the Israeli prime minister), markets will calm, even if the midst of uncertainty hasn't fully cleared.

However, if this is a genuine rewiring of global trade and the end of globalisation as we know it, markets and economies will continue to get battered.

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As one Trump supporter, billionaire Bill Ackman - who opposes the tariffs - put it, President Trump has launched a "global economic war against the whole world" that will usher in an "economic nuclear winter."

It's time for all of us to buckle up.