The Wall Street Journal argues that now is the right time for regime change in Iran, recalling lessons from Iraq in 2003. The current situation resembles 1991, and President Trump's decision to target Iran's nuclear program and engineer a quick ceasefire is seen as a strategic success. However, Iran's threat extends beyond its nuclear ambitions, as its support for proxy terrorist groups jeopardizes regional stability and American lives. Additionally, Iran's illegal oil exports undermine U.S. pressure on Russia amid the Ukraine conflict. Containing Tehran could also enhance U.S. leverage over China, which relies on Iranian and Russian oil. The pressing question is whether to act now or wait for regime change. History suggests immediate action is necessary.