The American drone attack that killed Iranian Gen. Qassem Soleimani last week is the latest move in a low-level war between Iran and the U.S. that has been waged with varying degrees of intensity for over 40 years – and is likely to continue long into the future. Some people fear that recent events will escalate the long conflict into a costly all-out war between the two countries. Others may welcome what they see as the necessary and inevitable showdown leading ultimately to regime change in Tehran. The killing of Soleimani – the most prominent military figure in Iran and close to Supreme Leader Ayatollah Ali Khamenei – can be seen as an escalation and will almost certainly provoke Iranian retaliation. President Trump's boast of ordering the killing of Soleimani may further increase pressure on Iran to respond.