Both the Wa and its southern ally Mongla are closely following the gradual build-up of the Burma Army along its border in Mongkhark and Mongyang, north of Kengtung, according to sources coming to the Thai-Burma border.

"Although reports are still sketchy, as the details of the build-up are still lacking, there is little doubt that new units are coming and establishing new outposts in the two townships," said a border watcher in Maesai, opposite Tachilek, 160km south of Kengtung.

Both the Wa and Mongla, officially National Democratic Alliance Army-Eastern Shan State (NDAA-ESS), are also reinforcing to prevent any attempt by the Burma Army to cut off the geographical links between them.

"The Burma Army appears to be trying to reclaim areas under Mongyang township's jurisdiction that were lost to the Wa and Mongla forces before the ceasefire (in 1989)," he said.

Mongpawk, Mongphen and Hotao, under Wa control, and Hsaleu, under Mongla control, are considered part of Mongyang. Both have refused to return the areas to the Burma Army although the latter had offered to compensate by returning Markmang [Mawfa] to the Wa and recognizing Mongla, formerly part of Kengtung, as a separate township. "If we accept it, the Burma Army will take control of the areas between Mongla and us [Wa]," a Wa officer had earlier told SHAN. "Mongla will be easily occupied and the Wa will be surrounded on all sides – except on the Chinese side – by the Burma Army."

Both the Wa and Mongla commanders refused to comment on the current tension. Clashes were reported but later found out to be false. "What is true is that the Burma Army has dispatched spies, both local and its own, to reconnoiter, many of whom have been caught by both Wa and Mongla," said Lt-Col Gawnzeun, Commander of the anti-junta Shan State Army (SSA) South, whose units are operating in Mongyawng, adjoining Mongla's southeastern rim.

China, according to earlier reports, has warned both sides against starting a war along its border. "What we are witnessing therefore is just war in the shadows," quipped the border watcher.

The Wa have been granted a Self-Administered Division (SAD) status in the newly approved constitution drawn by the ruling military council.