Brett McGurk is a CNN global affairs analyst who served in senior national security positions under Presidents George W. Bush, Barack Obama, Donald Trump and Joe Biden.

Wars often end somewhere different from where they begin.

The current conflict with Iran has been plagued by ill-defined and shifting objectives, from aspirations of regime change to more focused aims of degrading Iran’s nuclear and military capabilities.

Nearly six months in, it has evolved into something else entirely: a struggle over who controls the Strait of Hormuz and, with it, one of the world’s most important arteries for global energy. Iran has demonstrated both the capability and willingness to target commercial shipping passing through the strait unless conducted under rules Tehran prescribes.

The US – and much of the world, including all the Gulf states adjacent to the strait – has rightly deemed that unacceptable.