(BSS/AFP) - Asian stocks fluctuated Tuesday while oil edged up as investors assess a US plan for the "economic asphyxiation" of Iran, while tech firms struggled following another down day on Wall Street and ahead of earnings from chip titan Nvidia.

With the war against Tehran now in its sixth month, Treasury Secretary Scott Bessent said the White House was declaring an "economic D-Day" on the Islamic republic and threatened to hit countries that trade with it.

The threat comes with talks to reopen the Strait of Hormuz stalled and neither side showing any sign of backing down -- pushing oil prices up for most of August, which has in turn fanned long-term inflation fears and put pressure on bond markets.

"Around the globe, our objective is to sever every economic lifeline that sustains this tyrannical regime until Tehran stands alone," Bessent told journalists Monday.

"We are going to hold everyone accountable, and this is economic asphyxiation of this regime," he said, adding that countries not joining US sanctions would "share" in Iran`s isolation.

President Donald Trump was making phone calls to world leaders with requests to stop interactions with Tehran, Bessent said.

The Treasury Department said Iran`s digital assets, technology, gold, aviation and shipping sectors would be targeted for sanctions.

Both main contracts fell more than two percent Monday as Bessent`s comments appeared to suggest the US will hold off military action, but they ticked higher in early Asian trade.

His "increasingly aggressive economic campaign against Iran is designed to squeeze Tehran`s access to the global financial system while keeping the pressure economic rather than allowing the market to immediately price another military escalation", wrote Stephen Innes, global strategist at Quintex Intel.

"For now, oil appears to have heard the message that way, which is doing Washington the considerable favour of taking some inflation pressure out of the system."

Still, equities struggled as tech firms once again bore the brunt of selling, tracking a retreat in their counterparts on Wall Street.

Tech-rich Seoul sank more than two percent at one point as chipmakers SK hynix and Samsung retreated, while Hong Kong, Shanghai, Taipei and Manila were also off.

There were gains in Tokyo, Sydney, Singapore and Wellington.

The tepid performance comes ahead of much-anticipated earnings from Nvidia, which has become something of a bellwether for the AI boom.

With vast sums lavished on artificial intelligence investment over the past two years, markets are growing increasingly nervous about whether firms can deliver results to match.

And analysts have warned that even forecast-beating figures can sometimes not be enough.

Charu Chanana at Saxo Markets said: "Investors are not simply asking whether Nvidia can deliver another strong quarter. They are asking whether it can deliver enough upside to justify already-high expectations, especially with bond yields elevated."

Eyes will also be on other tech names` releases, including Salesforce and Marvell.

Also in focus is this week`s annual gathering of central bankers, economists and finance chiefs in Jackson Hole, Wyoming, where the Federal Reserve`s boss Kevin Warsh is due to speak.

His comments will be parsed for clues about monetary policy with inflation still stubbornly high and after Bessent said the Treasury would buy back more of its own bonds to push down borrowing costs after the 30-year yield surged to a 19-year high.

The Canadian dollar edged slightly higher after retreating against the US dollar Monday as Trump vowed to double tariffs on vehicles from its neighbour, fanning a trade war.

The US president`s threat comes after the two failed Friday to reach a deal to avert new 50-percent US tariffs on select Canadian goods. The duties took effect Saturday, and Ottawa laid out plans for retaliation.

- Key figures at around 0230 GMT -

Tokyo - Nikkei 225: UP 0.1 percent at 65,598.68 (break)

Hong Kong - Hang Seng Index: DOWN 0.3 percent at 25,452.91

Shanghai - Composite: DOWN 0.1 percent at 3,876.42

Dollar/yen: UP at 159.21 yen from 159.15 yen on Monday

Euro/dollar: UP at $1.1666 from $1.1663

Pound/dollar: UP at $1.3637 from $1.3629

Euro/pound: DOWN at 85.55 pence from 85.57 pence

West Texas Intermediate: UP 0.7 percent at $85.57 per barrel

Brent North Sea Crude: UP 0.5 percent at $92.59 per barrel

New York - DOW: UP 0.3 percent at 53,417.16 (close)

London - FTSE 100: UP 0.4 percent at 10,854.32 (close)