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.