Burma's ruler Senior General Than Shwe
The mystery surrounding recent bombings in Burma is highlighting uncertainties about the ruling junta's control of the security situation. Many regional experts say the violence may indicate new tensions within the military government.

The May 7 bombings at a trade center and two supermarkets killed at least 19 people, and injured as many as 150 others. The bombings were the deadliest breach of Rangoon's generally tight security in the past few years.

They shocked the city and the country's military leadership, which appears to be under increasing internal as well as external pressure.

Diplomats in Rangoon in the past few days said there have been no fresh developments in the case, nor concrete evidence of who was behind the bombings. Theories range from one of Burma's many rebellious ethnic minority groups to the government itself, setting off a bomb to create an excuse for its tough rule.

Garry Rodan is the director of the Asia Research Center at Western Australia's Murdoch University.

"It does seem to me the obvious question is whether or not this was something internal to the regime to try to justify its continued hard line, or whether it's a genuine attempt by opponents of the regime to create mayhem," Mr. Rodan said.

The Burmese government says the bombings were the work of "terrorists" who trained in a neighboring country with the assistance of a "superpower nation" - apparently references to Thailand and the United States. Both countries dismiss the allegation.

Thai Foreign Ministry Spokesman Sihasak Phuangketkeow says the allegation by Burma, also known as Myanmar, puzzles his government.

"We're a little bit perplexed by the statement that has been made by the minister of the Myanmar government, and we believe that, if they have any information in that regard they should let us know," he said.

One Burmese official has said three ethnic Karen rebels are suspected of carrying out the attack.

The explosions marked a deadly change in Burma's political climate, which was already uncertain after the purge of Prime Minister Khin Nyunt last October.

Khin Nyunt also was chief of military intelligence, and many of his backers were ousted from the government along with him. Some regional political analysts say former intelligence officials, angry over the loss of their privileges, may have been behind the bombings.

Debbie Stothard, coordinator for the rights group, Alternative ASEAN Network on Burma, says internal political and economic conflicts have added to the confusion over who was responsible for the bombings.

"It is now emerging that it's not just a case of tensions between supporters of former Prime Minister Khin Nyunt - who lost money because of the purge - but also there seems to be tension between Senior General Than Shwe and General Muang Aye," she said.

Burma's government, the State Peace and Development Council, came to power during a bloody crackdown against pro-democracy action in 1988. Senior General Than Shwe and his deputy, General Muang Aye, lead the government.

In the past, Than Shwe played a balancing role between Khin Nyunt, who was viewed as something of a moderate, and Muang Aye, a hard-liner.

Burma experts note that two of the bombing targets were partly owned by Muang Aye's daughter.

Khin Nyunt had negotiated cease-fire agreements with more than a dozen minority groups that have fought the Rangoon government for decades. However, some independence minded rebels continue fighting in many areas of the country.

Panitan Wattanayagorn, a political scientist at Bangkok's Chulalongkorn University, foresees instability in the short term, as the leadership strengthens its control.

"The government of Burma has not been able to stabilize the situation on the borders and, increasingly, in the big cities," he said.  "And that is quite problematic, given the instability that has been taking place in Burma. Now, it seems like the conflict within the leadership, as well as conflict with the armed separatist movement, has been intensifying."

The military government now appears to be struggling on several fronts to manage its control over Burma.

Adding to the government's troubles is rising international pressure over plans for Burma to become the chairman of the Association of South East Asian Nations in 2006. The United States and the European Union have indicated they might boycott ASEAN meetings, if Burma takes the helm, without making substantial political reforms.

Among their concerns are the continued detention of pro-democracy opposition leader Aung San Suu Kyi and a litany of human rights abuses.

Fifteen years ago this week, the National League for Democracy won national elections, but the military never allowed the party to take power. Aung San Suu Kyi and many other leaders of the party have spent most of the years since then in jail, or under house arrest.

Many ASEAN politicians have urged Burma to give up its chance to lead the group. The May 7 bombings may add pressure on Rangoon to do so because of concerns about security.