The dollar index held near 99 on Tuesday after rising in the previous session, supported by safe-haven demand as the US moved to isolate Iran from the global financial system. Treasury Secretary Scott Bessent said Monday that sanctions would target countries doing business with the Islamic Republic, underscoring the dollar’s central role in international trade. The currency nevertheless remained close to three-month lows after the Treasury Department expanded its buyback program for long-dated government debt to contain rising borrowing costs. Markets questioned whether the measure would provide more than temporary relief, while concerns resurfaced about the risks of a US debt crisis and further dollar weakness. Investors are awaiting the latest US PCE price index data and Fed Chair Kevin Warsh’s speech at this week’s annual Jackson Hole symposium for indications about the monetary policy outlook.