US equity futures sank with the euro while the safe-haven dollar as well as yen were in demand on Monday after the Western nations imposed fresh sanctions on Russia owing to its invasion of Ukraine, including blocking some banks from the SWIFT international payments system.

US 10-year Treasury futures rose a full point, while the Russian rouble indicated as much as 25% weaker at a new record low around 112 per dollar.

The fall in the rouble came after Russian President Vladimir Putin put nuclear-armed forces on high alert on Sunday, the fourth day of the biggest assault on a European state since World War Two.

At the same time, Asia-Pacific stock markets were higher in early trade, with Australia's benchmark rising 0.39% and New Zealand's up 0.74%.

That was the knock-on effect of Wall Street gains from Friday, when the S&P 500 closed up 2.51%, said Kyle Rodda, a market analyst at IG Australia.

US emini stock futures though were pointing to a 2.32% drop at the restart.

"We had a deluge of very negative information over the weekend," Rodda said.

"My sense is there's not going to be much staying power behind this particular move (in Asia-Pacific stocks), considering we're talking about financial stability risks, and sprinkle over that the threat of nuclear war."

"The FX market seems to be the best signal (of market sentiment) at the moment."

The euro slid 0.9% to $1.1165 and 0.85% to 129.15 yen, while the risk-sensitive Australian and New Zealand dollars sank 0.76% and 0.85%, respectively.