Karen National Union (KNU) brigades have been instructed to open fire when junta troops cross clear lines of territorial control amid a Myanmar military offensive centred on the town of Lay Kay Kaw in Kayin State, according to sources close to the ethnic armed group.

One of those sources told DMG that the directive was communicated to all seven KNU brigades in response to the Myanmar military’s recent hostilities with the Karen National Liberation Army (KNLA), which is the KNU’s armed wing.  

“The order was issued at a meeting last night as the military council was unjustly reinforcing its forces,” the source said on Monday.

At least 20 junta soldiers including a military officer were reportedly killed and two KNU members were injured in fighting between the Myanmar military and a joint force of KNLA, People’s Defence Force (PDF) and Democratic Benevolent Army (DKBA) troops on December 19.

During Sunday’s hostilities, the Myanmar military fired heavy artillery shells at Mae Htaw Tha Lay village, destroying at least 10 houses. More than 1,000 locals affected by the fighting have fled to Mae Sot refugee camp in Thailand, according to an aid worker who spoke on condition of anonymity.

“The scene yesterday evening was really disappointing,” the aid worker added. “Refugees are fleeing to Thailand, hand-in-hand across the Thaungyin [aka Moei] River. There are other, elderly people on the Myanmar side, so some remain in Myanmar. The refugees are being rescued by boats. Currently, the number of refugees is over 3,000. Due to the cold weather, refugees are facing many difficulties.”

Fighting between the Myanmar military and the KNLA in and around Lay Kay Kaw has forced more than 10,000 civilians to flee their homes near the Thai border in recent days, and two elderly men were injured when artillery shells fired by the Myanmar military fell on the Thai side.

The Royal Thai Army has reportedly informed its Myanmar counterpart that it will retaliate militarily if more artillery shells cross the border. Thai military helicopters have been seen flying in the skies over Mae Sot.

The Myanmar military has reportedly sent reinforcements from Yangon, Bago, Taungoo, Myawady, Kyonedoe, Hpa-an and Mawlamyine amid the Lay Kay Kaw hostilities.

Tensions between the KNLA and the Myanmar military escalated into outright armed conflict on December 15, and fighting has continued to date.