SINGAPORE - Global shares and US Treasuries were volatile on Tuesday, reversing a brief relief rally from early in the session in the first few hours of Donald Trump's new presidency after he announced plans for trade tariffs on neighboring countries.

US markets were closed for a holiday on Monday, so the first responses to Trump's inauguration were felt during Asian trade on Tuesday.

Trump said that his administration is mulling imposing 25 percent tariffs on Mexico and Canada as soon as Feb 1 - a move which doused investors' hopes of a delay after they had been cheering the brief mention of tariffs in his inauguration speech.

Trump's plans for hefty import tariffs and tax cuts are a key area of focus for financial markets on the view that such policies will stoke inflation and run the US economy red hot again, which would boost the dollar and hurt bonds.

US stock futures swiftly reacted to the latest developments by reversing their gains from earlier in the session, with Nasdaq futures sliding 0.4 percent while S&P 500 futures fell 0.25 percent.

EUROSTOXX 50 futures and FTSE futures lost 0.3 percent each, while Japan's Nikkei similarly reversed early gains and last traded 0.4 percent lower.

"At some point, we are quite certain that Trump will start to move on the tariff measures ... It's quite clear what his intent is," said Khoon Goh, head of Asia research at ANZ.

"The fact that he hasn't addressed this on day one doesn't mean that it is off the agenda. It is definitely firmly on the agenda, it's just that we have to wait and see what shape or form he takes."

MSCI's broadest index of Asia-Pacific shares outside Japan ticked up 0.2 percent.

In the Treasury market, the benchmark 10-year US Treasury yield pared some early losses but remained four basis points lower at 4.5682 percent. Yields move inversely to bond prices.

The two-year Treasury yield last stood at 4.2424 percent.

The overall market moves reflected a sharp reversal from earlier in the session after Trump had stopped short of imposing new tariffs in the first few hours of his presidency, which in turn sent the dollar sliding broadly.

The greenback has since recouped those losses, leaving the euro trading 0.36 percent lower at $1.0378, while sterling tumbled 0.4 percent to $1.2282.

Against the Mexican peso, the dollar surged more than 1 percent to 20.69. It also rose 0.8 percent against the Canadian dollar to C$1.4423.

"Investors now face a new reality where sudden policy shifts and increased volatility are the norm," said Boris Kovacevic, global macro strategist at Convera.

"Trump is expected to push for trade protectionism and economic nationalism, but the key question is how aggressively he will pursue this agenda."

In commodities, oil prices weakened after Trump announced a plan to maximize US oil and gas production by declaring a national emergency.

Brent crude futures ticked up 0.06 percent to $80.19 a barrel but languished near more than one-week low. US West Texas Intermediate crude futures sank 1.46 percent to $76.74 per barrel from Friday's close. There was no settlement on Jan 20 due to the US public holiday.

Spot gold gained 0.14 percent to $2,712.20 an ounce.