Shares flat in Asia before Iran sanctions news, Nvidia results

Asian share markets were flat, and oil prices eased as investors awaited details of threatened U.S. sanctions on Iran due later in the session. The Canadian dollar dipped as a trade war loomed with its southern neighbor. Investors are also anticipating Federal Reserve Chairman Kevin Warsh's speech in Jackson Hole for clarity on U.S. interest rates, with markets implying around a 40% chance of a Fed rate hike by September 16 and fully pricing in a move by December. Treasury Secretary Scott Bessent's recent announcement of at least a doubling in bond buybacks, aimed at restraining a rise in yields, has had limited success so far.