Following a series of militant rocket attacks against the Kabul airport, an apparent attempt to target Defense Secretary James Mattis, the US responded with an airstrike to support a military operation against those responsible.

As is so often the case with US airstrikes, it didn’t go to plan, and instead of hitting the militants, officials say the missile “malfunctioned” and hit civilians. They’re so far refusing to confirm exactly how many civilian casualties there were.

A statement was issued expressing deep regret for “harm to non-combatants,” and promising an investigation into the malfunctioning missile. This is, of course, hardly the first time a US airstrike in Afghanistan hit civilians.

It’s not clear why the US carried out an airstrike in the densely populated city in support of an ongoing operation, as the reports from the Afghan government suggested they had the situation well in hand.