U.S. lawmakers have increasingly used the debt ceiling to re-litigate congressional spending, risking default and sparking debate over whether to abolish the ceiling.

The threat of climate change and the rise of China have prompted renewed debate about the U.S. government’s role in shaping the economy.

For many policymakers, economic sanctions have become the tool of choice to respond to major geopolitical challenges such as terrorism and conflict.

U.S. and international sanctions have battered the Iranian economy and brought Tehran to negotiate over its nuclear program. Lifting them is central to a deal but will be a complex process.