But identity of bombers not known; no link yet to four arrested in Bang Na
Bombers who threw grenades at the Bangkok Shutdown march on Banthad Thong Road and at the rally site at Victory Monument over the past few days may be from the same group and well trained – but nobody knows exactly who they are or what they want.
Four suspects were arrested in Bang Na several days ago on charges of possessing war weapons but there remains no solid evidence to link them with the two attacks.
Metropolitan Police spokesman Adul Narongsak has suggested that the bombers at Banthad Thong Road had joined the protesters and detonated the devices while marching with them on Friday. He argued that it would have been difficult to drop a grenade from a building nearby as there were trees and utility wires in the way.
However, a bomb expert disagreed, saying the RDG-5 grenade had a range of 15 metres, so it would be tough for the bomber to detonate it and leave safely. It was highly possible that he had dropped it from a window in a deserted building where he had been hiding out.
The attack at Victory Monument was different, as the bomb appears to have been thrown from outside. The thrower was well trained. The way he hurled the grenade, as seen on surveillance footage, was very professional.
“Military or police always throw the grenade in this manner,” he said.
Ordinary people could not lob a hand grenade across barriers to hit a target precisely, he said.
However, it is hard to conclude that bombers in the two attacks are Thai security personnel, as Russian-made RDG-5 grenades are not used by the Thai military or police.
Neighbouring countries such as Cambodia, Laos and Myanmar use this type of grenade, a security source said, adding it was also available via the black market on the borders.
The pins of grenades found at the scene were relatively new, suggesting they were from the same lot that was recently smuggled in, he said.
Songphon Eiambutr, a former adviser to the House Committee on Military Affairs, said using such a grenade made it difficult for officials to trace the attackers.
An RDG-5 grenade is quite small. An average soldier can heave it a very long distance, which means he would be safe and could sneak away easily as it went off.
A police source said the serial numbers 48 and 152-82Y3PRM-2 seen on the fuses of the grenades suggested nothing more than they were the same type of bomb. They may not be a clue to identify the attackers who used them, he said.