The Office of Commander-in-Chief issued a statement yesterday that KIA/TNLA insurgent groups jointly carried out attacks on a police camp on Pankham Bridge, head of Nankham Myoma People's Militia Group U Aike San's house, Manwain gate and Naungyan village near Pankham Bridge.
Rights defenders say clashes in northern Myanmar near the China border have ramped up since January as the worldwide community focuses on the Rohingya crisis in the west of the country.
The army has been accused of systematic human rights violations against the ethnic Rohingya Muslim minority in the western state of Rakhine, forcing more than 700,000 Rohingya to flee to neighboring Bangladesh since last August.
Of the 18 civilians killed in the attack that began at 5 a.m., 16 were men and two were women, said Zaw Htay.
He called the operation "terrorism".
"This is not the ethnic rights movement", said government spokesperson, Zaw Htay.
The assault was in retaliation for recent attacks on TNLA outposts and for a military push in Kachin state to the north, where an offensive against the Kachin Independence Army, a TNLA ally, has displaced more than 6,000 people in the past month, he said. "This is a terrorist attack".
Aye Myint, a police officer in Muse, said the death toll was 19, and that TNLA fighters used small arms as well as mortars.
It is unclear if members of the powerful KIA took part in the attacks yesterday.
The security police fought back against insurgents in cooperation with Paysay People's Militia Group and Myoma People's Militia Group.
Myanmar's military frequently clashes with several groups, which say they are fighting for greater autonomy for ethnic minorities in the area, through which much of Myanmar's foreign trade flows.