By Tom Westbrook

SINGAPORE, Aug 24 (Reuters) – A wavering dollar teetered near multi-month lows on Monday in a market unsettled by the U.S. Treasury’s promise to buy back more long bonds, while traders awaited details of sanctions on Iran ‌and on policy speeches this week in the U.S. and Japan.

The Canadian dollar slipped 0.2% in early trade, to ‌C$1.3798 per dollar, after trade talks with the U.S. collapsed and Washington imposed 50% tariffs on Canadian goods, with Canada retaliating in kind.

The Australian and New Zealand dollars ​traded just shy of three-month highs at $0.7171 and $0.5979 respectively.

The euro was comfortably above $1.16 at $1.1685 while the yen kept to the strong side of 159 per dollar.

Friday data showing the strongest U.S. services growth in nearly two years in August held off dollar sellers in steady early trade.

The dollar logged its largest weekly drop against bitcoin in nearly three-and-a-half years on Sunday and it’s been sliding sharply on gold over revived fears ‌the currency will suffer if the U.S. tries ⁠to hold down yields.

Long-end yields have been climbing globally on a combination of a solid economic growth outlook, rising inflation expectations and nerves about ballooning sovereign debts.

Last week, after 30-year yields hit almost two-decade highs, ⁠the U.S. Treasury announced it would double buybacks at the long end to $4 billion per operation.

The size is paltry in a market worth $32 trillion but the interventionist signal spooked traders and hit the dollar.

“The U.S. Treasury’s attempts to artificially hold down long-term bond yields appears to be reigniting the $US ​debasement ​trade,” said Shane Oliver, head of investment strategy at Australian financial services firm ​AMP.

The mood was keeping Australian dollar above 71 cents, ‌he said. [AUD/]

Sterling was firm at $1.3650 in morning trade and the yuan, which notched an eighth straight weekly rise last week, hovered near a 3/1-2 year high at 6.7222 per dollar. [GBP/][CNY/]

SANCTIONS AND WARSH

Later on Monday, at 1800 GMT, U.S. Treasury Secretary Scott Bessent is due to hold a press conference after threatening “the toughest sanctions in history” on Iran, with markets focused on whether he will target China.

Iran’s foreign minister has dismissed the threat of new U.S. sanctions as a sign of desperation.

Market participants will also be hoping for some clarity on ‌the outlook for U.S. interest rates when Federal Reserve Chairman Kevin Warsh speaks ​in Jackson Hole, Wyoming, on Friday.

He is also sure to face questions about ​Treasury’s buybacks.

“Any comments on the balance sheet, duration supply, or ​term premium could move the long end more than the data itself. That said, given Warsh’s typically restrained ‌style, we aren’t holding our breath,” said BNY strategist ​Geoff Yu.

A Thursday appearance by Bank ​of Japan deputy governor Ryozo Himino will also be closely watched as a prelude to next month’s policy meeting. In particular, investors will be looking to see if he pushes back on a shift in market pricing to see a faster ​pace of hikes.

“Himino may signal the BOJ is ‌moving closer to another interest rate hike,” said Commonwealth Bank of Australia strategist Joe Capurso.

“However, any hawkish comments are ​likely to exert only modest downward pressure on USD/JPY. Developments in the U.S. bond market area are a more ​important driver of USD/JPY.”

(Reporting by Tom Westbrook; Editing by Edwina Gibbs)