The US president has lived up to his campaign pledges to resume his hardball trade diplomacy to extract concessions on a range of issues, including commerce, immigration and drug trafficking.

While the moves have jolted sentiment, equities have held up since Trump took office, with analysts saying measures have so far been less severe than feared.

Still, caution looms over trading floors as dealers brace for the next announcement out of the White House, with Maurice Obstfeld, senior fellow at the Peterson Institute for International Economics, saying "the degree of uncertainty about trade policy has basically exploded".

The latest US duties will take effect on March 12.

"Today, I'm simplifying our tariffs on steel and aluminum," Trump said in the Oval Office on Monday as he signed off on them. "It's 25 percent without exceptions or exemptions."

He also signalled he would look at additional tariffs on automobiles, pharmaceuticals and computer chips.

Charu Chanana, chief investment strategist at Saxo Markets, said: "These expanding trade actions beyond previous threats to Canada, Mexico and China are leading to potential new import restrictions and retaliation, signalling more bouts of volatility for investors.

"Tariffs are being used not just to tax imports but also as tools for national security, economic leverage and revenue generation, indicating a shift towards long-term economic policy rather than short-term trade disputes."

All three main indexes started the week on the front foot thanks to a rally in tech firms.

But Asia struggled to maintain its momentum from Monday, with Hong Kong, Shanghai, Singapore, Mumbai, Jakarta and Manila falling.

Seoul, Wellington, Bangkok and Taipei rose with London and Paris, though Frankfurt dipped. Sydney was flat.

The uncertainty fuelled by Trump's moves has pushed safe-haven gold ever higher. On Monday, it broke above $2,900 for the first time. It extended gains Tuesday to hit a new peak above $2,942.

Fears that Trump's tariffs, along with tax cuts and deregulation, will reignite inflation and force the Federal Reserve to keep interest rates elevated have sent the dollar up against most of its peers.

Readings on consumer and producer price indexes this week will provide a fresh snapshot of inflation, while Fed boss Jerome Powell is also due to give depositions to US lawmakers.

Both will be pored over for an idea about the bank's plans for rates, with forecasts for two cuts at most this year.

- Key figures around 0815 GMT -

Hong Kong - Hang Seng Index: DOWN 1.1 percent at 21,294.86 (close)

Shanghai - Composite: DOWN 0.1 percent at 3,318.06 (close)

London - FTSE 100: UP 0.2 percent at 8,784.63

Tokyo - Nikkei 225: Closed for a holiday

Euro/dollar: DOWN at $1.0305 from $1.0308 on Monday

Pound/dollar: DOWN at $1.2345 from $1.2364

Dollar/yen: DOWN at 151.96 yen from 151.97 yen

Euro/pound: UP at 83.48 from 83.35 pence

West Texas Intermediate: UP 0.7 percent at $72.83 per barrel

Brent North Sea Crude: UP 0.8 percent at $76.45 per barrel

New York - Dow: UP 0.4 percent at 44,470.41 (close)

dan/pbt

INDEX CORP.

Dow