Asian share markets dithered on Monday as the threat of imminent tariffs lurked in the background, while bitcoin surged on news it would be included in a new US strategic reserve of cryptocurrencies.

US President Donald Trump on social media announced five digital assets he expected to include in a new reserve, including bitcoin, ether, XRP, solana and cardano.

Bitcoin, the world's largest cryptocurrency by market value, shot up more than 11 percent to US$94,110, while ether, the second-largest cryptocurrency, climbed 14 percent to US$2,528.

MSCI's broadest index of Asia-Pacific shares outside Japan was flat, though Japan's Nikkei rose 1.1 percent, helped by a softer yen.

S&P 500 futures and Nasdaq futures were both up 0.1 percent, having staged a late rally on Friday after a week of heavy losses.

On Sunday, US Commerce Secretary Howard Lutnick said tariffs on Canada and Mexico would go into effect on Tuesday, but that Trump would determine whether to stick with the planned 25 percent level.

An extra 10 percent levy on Chinese imports is also due to come into effect this week, just as the National People's Congress opens its annual session on Wednesday. (Reuters)