Asian equities advanced and government bond yields fell early Thursday, bolstered by the U.S. Treasury's plans to ramp up bond buybacks--a move aimed at easing pressure on a market that had recently driven borrowing costs to their highest levels in nearly two decades.

The Treasury Department said Wednesday that it would double its buyback operations for bonds maturing in 10 years or more, to at least $4 billion per operation from $2 billion currently, effective Sept. 9. The announcement intensified an overnight decline in Treasury yields, which had hit multiyear highs in recent sessions.

"It is a bit of notice of intent that the Treasury is seeing what's going on in longer-end yields and is taking a couple of steps to respond there," said Taylor Nugent, senior economist at National Australia Bank, in a podcast. "What the Treasury has done is kind of bought a bit of reprieve from the [rising yield] trend, and we've certainly seen that in a fallback in longer-end yields," Nugent added.

Yields on Japan's 10-year sovereign debt fell 5.5 basis points to 2.835%, while Australia's 10-year government bonds declined 3 basis points to 4.9950%. New Zealand's 10-year sovereign securities dropped 2 basis points to 4.6900%. Bond yields move inversely to prices.

"While buybacks alone are unlikely to alter longer-term fundamentals, they do signal willingness by policymakers to lean against further yield increases," said Lloyd Chan, a senior currency analyst at MUFG Bank.

Asian equities mostly rose. South Korea's Kospi jumped 5.4%, Japan's Nikkei Stock Average gained 1.3% and Hong Kong's Hang Seng Index climbed 1.0%.

Regional currencies traded mixed after minutes from the Federal Reserve's July meeting indicated that more officials favored raising interest rates. The U.S. dollar was little changed at 1.2713 Singapore dollar but was 0.4% higher at 1,393.60 won, according to LSEG data.

"Moderating Fed tightening expectations and Treasury efforts to contain long-end yields could continue to cap dollar upside," MUFG Bank's Chan said. "This should continue to provide a supportive backdrop for Asian currencies in the near term, particularly those with resilient domestic fundamentals, stronger external balances and positive exposure to global tech cycle," he added.

Meanwhile, oil futures climbed after President Trump threatened Iran with an "economic d-day," reflecting mounting frustration over the lack of progress in reopening the Strait of Hormuz and reaching a deal to end the nearly six-month-long conflict.

Trump said on Wednesday evening he would launch a major economic campaign against Iran and any entity that does business with the regime. He also said it would be "the MOST CRUSHING ECONOMIC OPERATION EVER TAKEN AGAINST ANY COUNTRY!" Trump did not specify what actions the U.S. would take beyond existing heavy sanctions against Tehran.

Front-month West Texas Intermediate crude oil futures were last up 0.3% at $86.07 a barrel, and front-month Brent crude oil futures were 0.5% higher at $92.05 a barrel, according to ICE data.