Regime change refers to any effort by a foreign power, overt or covert, to remove a leader and/or the political structure that controls a nation-state. These efforts are usually military in nature but can also involve diplomatic, economic, and informational tools. These policies are often used to promote democracy, advance economic interests or other geopolitical goals. They are a serious departure from the principle of Westphalian sovereignty in which nation-states enjoy a presumption of sovereignty over what happens inside their borders.
While regime change has been a staple of US foreign policy for decades, the results are rarely as desired. The Arab Spring, for example, saw some countries transition to democracy, while others descended into conflict and authoritarian resurgence. Even in the case of Iraq, the ousting of Saddam Hussein did not lead to a more peaceful Middle East or a more US-friendly regime, and instead created a power vacuum that allowed Iranian influence to expand and gave rise to ISIS.
Despite a scholarly consensus about the problems that typically accompany regime-change operations, many in the policy community continue to call for ousting illiberal regimes using force. The more that policymakers understand the challenges and limits of regime change, the better prepared they will be to avoid its pitfalls.