BANGKOK (Reuters) - Unprecedented aerial attacks on ethnic Kachin rebels by Myanmar's military have raised doubts about whether the retired generals in a government hailed for its reforms have really changed their harsh old ways.
Assurances by the quasi-civilian government that it wants a peace deal with the Kachin Independence Army (KIA) and that the military is exercising "maximum restraint" are starting to ring hollow as jets and helicopter gunships take to the air.
The 18-month conflict is back under the spotlight, with U.N. Secretary-General Ban Ki-moon voicing concern last week about reports of air strikes in Kachin State. The U.S. State Department said they were "extremely troubling".
Western countries that suspended most sanctions as a reward for political, social and economic reforms after the new government took power in March 2011 are now in a tricky spot.
Questions have been raised about the sincerity, or authority, of the former soldiers who had convinced them of their "irreversible" course of liberalisation when they ended nearly half a century of military rule.
"Sceptics had warned the international community not to get too caught up in all the excitement of the changes going on," said Christopher Roberts, a Myanmar expert at the Australia National University.
"This escalation is enough to spark a debate on whether sanctions were removed too soon."
The United Nations has repeatedly demanded humanitarian access to an estimated 70,000 people displaced by fighting that resurfaced in June 2011, ending a 17-year truce agreed after decades of bloody battles. The number of casualties is unknown, but they are estimated to be high on both sides.
The KIA says it is under attack in seven areas and that the military wants to seize its headquarters in Laiza, close to the Chinese border. It says the military has been using air strikes since December 24 to try to weaken the rebels and force them to the negotiating table -- claims the government strenuously denies.
Despite 11 rounds of peace talks, the KIA is the only ethnic minority army that has not agreed to a ceasefire with the government and won't stand down until it is offered a political deal. It says the current, army-drafted constitution won't guarantee their rights and wants it changed first.
State peace negotiators have a three-stage plan starting with a truce before any political dialogue, followed by a parliamentary congress in which permanent deals offering unspecified guarantees and concessions are signed.
The two sides have a bitter history and deep distrust. Political leaders are determined to ensure their people are treated fairly and get a share of the vast mineral resources they have long accused the military of looting.
"It's difficult to cease fighting while not knowing what will happen after," said KIA vice commander-in-chief, Major-General Gun Maw. "What should we do after a ceasefire? That's the answer we're looking for," he told the 7-Day News journal.
The decision to use air power against ethnic militias, a tactic unheard of even under military rule, runs counter to reformist President Thein Sein's assurances that troops were acting only in self defence.
Official Myanmar newspapers have said air support was used on December 30 to thwart KIA fighters who had occupied a hill and were attacking logistics units of the Tatmadaw, as Myanmar's military is known.
The former junta heavyweight has twice publicly ordered the military chief, a protege of reviled former dictator Than Shwe, to ensure troops don't launch any offensives. The recent escalation has raised questions about him that are almost impossible to answer in a country where the inner workings of the leadership in Naypyitaw remain highly secretive.
Zaw Htay, a president's office spokesman, said on Friday troops were responding defensively to KIA aggression and destruction of transport and power infrastructure and the army was committed to protecting the civilian population.
Nobel laureate Aung San Suu Kyi, now a lawmaker, has always urged a cautious approach to the changes. While lauding Thein Sein for his leadership, she has repeatedly said the role the military plays in Myanmar will dictate the country's future.
Thein Sein and his loyalists appear to be driving the reforms but the extent to which he controls the Tatmadaw remains unclear. Diplomats and analysts say either he is insincere about peace or the military is acting independently.
"He's just Mr. Nice Guy, the human face to the world and he has no authority to tell the army what to do," said Bertil Lintner, a journalist, author and expert on Myanmar's ethnic conflicts, who recently visited Kachin State
"Fundamentally, nothing has changed, it's the same people in power, they're just much more clever at managing things."
A more aggressive approach to the conflict could be embarrassing for the United States, which welcomed Thein Sein to Washington in September and has offered support to try to reform Myanmar's military, including an invitation to observe the annual U.S.-led Cobra Gold exercises in Thailand.
Any indication the military was pulling rank over the civilian government might concern foreign firms planning to invest in a country with a power structure dominated by retired or serving soldiers and plagued by vested interests.
The military remains a major player in many industries through its Myanma Economic Holdings Ltd and the Myanma Economic Corporation, both blacklisted by the U.S. Treasury Department. Those firms, or their close business allies, might not take kindly to competition.
The international community has been guarded in its criticism, wary not to upset Myanmar's notoriously thin-skinned rulers and drive them back into China's orbit. China was Myanmar's lifeline when sanctions were in place and once backed the KIA.
An alliance of Kachin groups issued an open letter on Friday urging the International Crisis Group to reconsider presenting Thein Sein with its highest peace award, accusing his office of a "duplicitous strategy" and "outright lies" that have undermined his credibility.
Experts say it's too soon to tell how Western powers would respond in the coming months, but confidence in Thein Sein could start to slow if the military follows its hard line against the KIA and risks killing off the peace process altogether.
"It doesn't look good for Thein Sein now and this (escalation) may not have been his intention," said Roberts.
"It's unlikely to threaten the broader reforms going on, but could damage the momentum and it'll certainly dampen the enthusiasm about progress."
Additional reporting by Aung Hla Tun in YANGON and Michael Martina in BEIJING; Editing by Paul Tait