Drugs and ethnic cleansing sparked the Thai-Burmese border clashes writes Peter Alford in Bangkok
The last poppies of the season are being tapped in dusty forest clearings in south-eastern Shan state and thousands of piles of 1.5kg opium "balls" are drying throughout the 100km strip abutting the Thai border.
"In contrast to the past two this has been a good season, perhaps a very good one," says Francis Christophe, a Paris based expert on Burma's narcotics industry.
Also this dry season, Tatmadaw (the Burmese armed forces) is waging a particularly vicious campaign against ethnic separatists that has driven - as intended - about 300,000 ethnic-Thai Shans into northern Thailand.
Tatmadaw battalions are operating alongside the United Wa State Army (UWSA), an industrial-scale supplier of the world's heroin and methamphetamines habits.
Now Tatmadaw's tactics of border-hopping to attack guerillas from behind, plus the Thai army's relatively new-found loathing of Burma's drug lords has triggered the most dangerous confrontation in a decade between the neighbours.
A Thai post was overrun last week and recovered by heavy force and on Sunday Burmese soldiers around Tachilek and the Thais in Mae Sai exchanged lethal barrages. At least 20 died and tension remains razor-sharp.
The confrontation has shattered hopes for a new Thai Prime Minister Thaksin Shinawatra's softer "forward engagement" policy to Rangoon.
While Defence Minister Chavalit Yongchaiyudh fostered cosy cross-border relations when he was Third Army commander, General Wattanchai Chaimuanwong is running a "zero tolerance" policy on border security and drugs.
Wattanchai's impossible task is stopping an estimated 10 tonnes-per-year of Wa methamphetamines moving into Thailand and he believes the fighting springs from tatmadaw complicity in the trade. "My opinion is that all Burmese unit commanders who caused the conflict should be put before a firing squad."
Like Wattanachai, Francis Christophe mocks the optimism of Interpol and UN agencies that Rangoon's generals are finally waging a war on drugs. "Everybody knows the Burmese army - at least at regional levels - are in the business," says Christophe. "They own most of the refineries."
Little of Burma's 2000-01 opium crop has yet to hit the market but Christophe notes Shan reports of a 15 per cent drop already in border prices for semi- refined heroin - a sure sign of something big in the pipeline. "Shan market information is always pretty accurate," says Christophe.
As it should be. Doubling as drug lords, Shan commanders used to dominate the trade.
Khun Sa pioneered the "narco-army" concept before he swapped the Shan cause in 1996 for a truce - a nice Rangoon compound and allegedly legitimate business.
The armed struggle - and, many believe, a slice of Khun Sa's old trade - has been continued by Colonel Yawd Serk's Shan State Army (SSA). But over the past two years the relocation from the northern hills of the 150,000 Red Wa, with the UWSA in the vanguard, has utterly changed the scene in south-eastern Shan state.
The UWSA's 20,000 fighters vastly outnumber the SSA and are lavishly equipped with the proceeds of the worlds's biggest single narcotics business.
They even have anti-aircraft guns, although not aimed at tatmadaw. The UWSA has been a "ceasefire group" for a decade.
As if to advertise their impunity, the Wa have turned Mong Yawn, a sleepy village overlooked by a Thai hilltop post, into a town of mansions, warehouses, paved roads and satellite dishes.
But the SSA has taken to attacking WA drug facilities to dramatise Yawd Serk's claims to be clean.
Thai military elements are widely suspected of assisting him since the Wa responded to the recent opium downturn by massively boosting their methamphetamines production. Unlike Wa heroin, which has a small, stable market in Thailand, Wa speed is fuelling devastating Thai social problems. That and sympathy for the Shans help explain why Wattanachai became something of a Thai national hero this week.
Peter Alford is the Australian's South-east Asia correspondent