Turkish troops backed by fighter jets and helicopter gunships have pursued Kurdish rebels into Iraq.
It follows overnight attacks on military installations in Hakkari province, near the Iraqi border, which killed at least 24 Turkish soldiers.
The attacks are thought to have inflicted the biggest loss on Turkish forces since 1993 and President Abdullah Gul has vowed to avenge them.
In recent months, violence between the army and Kurdish rebels has mounted. The attacks come a day after a blast in the south-east Bitlis province killed five police officers and three others.
Lisa Mullins talks with the BBC’s Jonathan Head in Istanbul.
The World is an independent newsroom. We’re not funded by billionaires; instead, we rely on readers and listeners like you. As a listener, you’re a crucial part of our team and our global community. Your support is vital to running our nonprofit newsroom, and we can’t do this work without you. Will you support The World with a gift today? Donations made between now and Dec. 31 will be matched 1:1. Thanks for investing in our work!