One of Myanmar's oldest ethnic minority rebel groups has warned major conflict with the military could soon erupt and has called for international intervention and protection of its people forced to flee fighting.
The Karen National Union (KNU) which until 2012 fought one of the world's longest-running insurgencies, is preparing its fighters for attacks on several fronts, as hostilities with the military reignite following a Feb. 1 coup.
With Myanmar in turmoil, the KNU and several other ethnic armies have sided with opponents of the junta, according to Reuters interviews with representatives of three such groups and the ousted civilian government.
Who Are the KNU?
The KNU is the dominant political organisation representing ethnic minority Karen communities in southwestern Karen State, officially known as Kayin State, bordering Thailand.
Their objective is self-determination for the Karen people in a region of about 1.6 million people, roughly the size of Belgium, where they are the ethnic majority.
Marginalised in then Burma's post-independence political process, the KNU started a rebellion in 1949, which it waged for nearly 70 years. One of its key grievances was the Bamar ethnic group's dominance of Myanmar's state and military.
It generates revenue from collecting taxes, including through illegal border trades and from mining and other development projects.
The KNU and its military wing, the Karen National Liberation Army (KNLA) have historically been one of the biggest adversaries of the Tatmadaw, as the military is known, and long resisted ceasefire agreements.
Activists have accused Myanmar soldiers of atrocities against the Karen, including murder, burning of villages, forced labour, torture and systematic rape of women and girls. The military has suffered many losses in battles with Karen guerrillas.
But after a quasi-civilian government initiated broad reforms in 2011, the KNU joined its Nationwide Ceasefire Agreement, touted as the first step towards a federal system.
The NCA has largely stalled, however, with deep scepticism among ethnic armies about the Tatmadaw.
The KNU has accused the military of bad faith by reinforcing troops and building defence installations in Karen territory, and of ceasefire violations that led to fighting.
Clashes in December displaced several thousand Karen and the KNU says troops have expanded to more Karen territory since the coup, despite junta leader Min Aung Hlaing vowing to honour the ceasefire. The KNU has urged the world to sever ties with the junta and KNU leaders have told Reuters the truce is over.
On Saturday, the KNU said its fighters had overrun an army command post, killing 10 soldiers. Military jets later launched air strikes on KNU territory for the first time in 20 years.
Exodus to Thailand
Thousands of Karen civilians have fled to Thailand, with many hiding in jungles. The KNU has urged Thailand to give sanctuary to its civilians if fighting intensifies, as it has done in the past.
There are conflicting accounts of Thailand's position on the refugees, with some reports and witnesses saying they were being blocked or sent back, prompting rebukes from activists.
The government said it has no policy of turning away refugees and accepts them on a humanitarian basis and refugees had returned to Myanmar voluntarily.
According to a plan seen by Reuters earlier this month, Thailand is bracing for a surge of refugees and has set aside areas for more than 43,000 people in its Mae Sot district.
The KNU says it is responding to appeals for help from coup opponents by sending fighters to protect protesters. Its troops are attacking Myanmar army positions and cutting off supply routes. In the north, the Kachin Independence Army (KIA) has launched similar attacks.
Three other guerrilla forces, including the Arakan Army in the western Rakhine state, have vowed to join what they called the "spring revolution" if the lethal crackdown on civilians continues.
Efforts are underway by remnants of the ousted government to create a joint resistance to the junta, including an interim constitution that would include a "federal army" to replace the military.
Despite having fewer troops and less firepower, by joining forces, the various ethnic armies could pose a significant problem to a Tatmadaw fighting on several fronts.
However, with some ethnic groups fighting each other, including those in Karen State and Shan States, an alliance seems less likely.
The military has also mastered divide-and-rule tactics over the years and succeeded in creating fissures within groups, while capitalising on their inability to present a united front politically and militarily.