Last week Thailand's National Legislative Assembly, a junta-stuffed body, impeached the country's former prime minister, Yingluck Shinawatra. She will now be barred from politics for five years and will face criminal charges in the Supreme Court which could see her imprisoned for ten years. 

Her sentencing came at the hands of the nine-month-old Thai junta, which seized power on 22 May 2014 with the promise of reform. What this verdict shows is that the stale politics the junta swore to remove are just as entrenched as ever.

Days after enacting martial law in May, then-army chief General Prayuth Chan-ocha seized power claiming it was the only choice in order to bring an end to the six months of crippling and increasingly bloody street protests. He promised to be an impartial peacemaker and to reform the country's broken political system, which has seen numerous coup d'etats and more than a decade of growing clientelistic politics.

Few disagree that Thailand's democracy was a mess. Yingluck's rice subsidy (for which she was impeached) was so poorly implemented that it ruined an otherwise healthy economy. Yet little evidence has been made public of how directly she was involved.

Among Thailand watchers, many of us pondered whether Prayuth's power grab could indeed offer the country's broken politics a much needed restart. Yingluck's impeachment is the final breath of this dying hope. While there have been many dubious moments in the junta's maladroit statecraft – among them broken promises for elections, continued martial law, the detention of youth for Orwellian 'attitude adjustment', and the appointment of a puppet parliament – this is the most desperate.

It shows that the junta is still prone to the beggar-thy-neighbour politics they ostensibly seized power to remove. Under the junta in August last year, charges were dismissed against Yingluck's opponents, protest leader Suthep Thaugsuban and former PM Abhisit Vejjajiva, for their role in the 2010 crackdown that left scores dead. So a dismissal of the Yingluck case would have been wise. At the very least, her case should have proceeded with transparent legal authority, and under an elected parliament with a valid constitution. 

Instead, this was a show trial.  

After a long period of cooling off, this impeachment rubs salt in old wounds. Despite a statement by Yingluck's Pheu Thai party that they will not encourage protests, the ruling has already angered her huge support base. Prayuth re-emphasised during the trial that martial law was still in place and any unauthorised assembly would be dealt with under that law. This, along with strict media control, has silenced Yingluck's supporters. But in  the long run, it will likely only make them louder and angrier.

Yingluck will now either be thrown into exile like her brother Thaksin or sentenced by the junta's Supreme Court to a decade in prison. If this happens she will become a martyr for her supporters, their own Aung San Suu Kyi.

Adding to worries of renewed political violence is the deterioration in the King's health. The passing of the much-revered 87-year-old leader would most likely lead to a 1000-day mourning process, during which no elections could be held and political manoeuvring frowned on. That would mean three more years of junta rule. That is if the highly politicised royal succession doesn't aggravate the already deep political divisions at all levels of society. 

The junta would be wise to live up to the promises that initially won at least tempered support from much of the population. Not pursuing the criminal charges against Yingluck would be a good step in that direction. Making public a detailed reform agenda or calling new elections as initially promised would also go a long way to regaining some confidence. Such confidence is crucial for businesses and the stability of the economy.

The US has a good opportunity to pursue these points next month when the the Cobra Gold joint military exercise is staged. Water cooler conversations should reiterate that the US will only accept military control and martial law in Thailand in the very short term, and that it must be accompanied by reform. Australia and other concerned states should make similar utterances.

If citizens aren't given a voice, mobilisation and mass protests will eventually spill over into violence. With the military in charge, that could be very bloody.

Photo by Flickr user APEC 2013.