The country's troubled western Rakhine state has seen a series of clashes in recent weeks between security forces and the Arakan Army (AA), an armed group calling for more autonomy for the state's ethnic Rakhine Buddhist population.
The area is one of the poorest in Myanmar and is scarred by deep ethnic and religious hatred.
A brutal army campaign in 2017 forced hundreds of thousands of Rohingya Muslims over the border into Bangladesh, operations justified by the army as a way to stamp out Rohingya militants.
The latest violence by ethnic Rakhine rebels culminated on Friday - Myanmar's Independence Day - in brazen pre-dawn raids on four police posts in Buthidaung township near the Bangladesh border.
Authorities said that the attack by hundreds of militants left 13 police officers dead and nine wounded before the army, known locally as the Tatmadaw, were able to provide back-up.
The AA said that three of its fighters had been killed, accusing the military of using the police stations as a base from which to fire heavy artillery.
"The president's office has already instructed the Tatmadaw to launch operations to crack down on the insurgents," government spokesman Zaw Htay told reporters in the capital Naypyidaw.