A year later, they find themselves looking back on a botched job, the fallout from which continues to reverberate through central Europe, heaping ever more embarrassment and disgrace on the Vietnamese government.
Thanh appeared in police custody in Hanoi a week after his disappearance and was later sentenced to two life terms for corruption – but only at the cost of severe damage to Vietnam’s international standing.
Former Slovak government leaders are the latest to find themselves in the spotlight, accused of helping Vietnam to get Thanh out of Europe.
Press reports in Germany and Slovakia say that a Slovak government plane was lent to a visiting Vietnamese delegation and was used to fly Thanh and his kidnappers to Moscow.
The long serving Slovak interior minister, Robert Kalinak, who has since resigned over another scandal, has denied charges that he knew Thanh was on board the plane. He volunteered for a lie detector test this week, saying the results backed up his claim not to have known.
His successor in the job is now coming under attack from the media and other politicians, who suspect that the current government is still trying to cover up the scandal.
The interior ministry has now given some ground, saying that police officers will be allowed to testify in an investigation into the case.
The Vietnamese embassy in Bratislava, meanwhile, is saying nothing.
Vietnam’s blanket denial that it had anything to do with the abduction looks increasingly like a diplomatic strategy based on desperation. The General-Secretary of the Communist party, Nguyen Phu Trong, had personally called for Thanh’s arrest beofre the abduction. He appears not to have considered the possibility that there would be lasting consequences.
Germany, meanwhile, is still seething from what it sees as a gross violation of its sovereignty.
A German court sentenced a Vietnamese man to three years and ten months in jail after he confessed to assisting Vietnam’s secret service in the operation.
The Czech Republic is also angered by reports that Prague was used as a logistical base and transit point by Vietnamese agents.
Vietnam now facing the real prospect of a breach in diplomatic relations with former close friends in Europe and the potential loss of a free trade agreement with the EU, which has still not been ratified.