- The US dollar emerged as the global reserve currency following World War 2 at the Bretton Woods conference in 1944. This established the dollar as the center of the international monetary system and gave the US vast economic influence through its ownership of the reserve asset.

- Throughout the late 20th century, US Treasury Secretaries worked to maintain the dollar's dominance and smooth the flow of global capital through interventions, the Plaza Accord, and espousing the "strong dollar" policy. This benefited the US economy but also contributed to manufacturing declines in places like the Rust Belt.

- The 2008 financial crisis tested the dollar's supremacy and revealed weaknesses in the US-led economic order. Treasury Secretaries Paulson and Geithner took aggressive actions to rescue the system through TARP and other measures.

- Under Obama and later Trump, the US increasingly relied on economic sanctions as a foreign policy tool, often targeting nations like Iran, Russia, and Venezuela. This risked overusing sanctions and raised doubts about dollar dominance.

- Trump took a more adversarial stance towards allies and rivals alike, openly questioning currency and trade policies. His Treasury secretaries struggled to maintain stability and confidence in the face of disruptions.

- The Russian invasion of Ukraine in 2022 prompted the most severe sanctions yet on Russia via the SWIFT banking system and Central Bank. This demonstrated the dollar's peacetime utility as a sanctioning tool but also its vulnerabilities if nations circumvent it.

- Maintaining the dollar's status will require deft diplomacy and prudent economic policies from future Treasury secretaries amid rising challenges to US global leadership. Geopolitical tensions and the weaponization of finance pose ongoing risks.