A Burmese court's ruling this week in the house arrest of Aung San Suu Kyi is once again drawing intense criticism of  Burma's military rulers.   Aung San Suu Kyi had her house arrest extended by 18 months, on charges the pro-democracy advocate violated an internal security law.  Meanwhile, diplomats are again working to coerce Burma's ruling junta to ease their crackdown on political opponents. 

If she serves her full sentence, the 64-year-old Burmese opposition leader will be prevented from taking part in elections next year - which critics say was the goal of the Burmese leadership. 

Aung San Suu Kyi  has already spent 14 of the past 20 years in detention, mostly under house arrest.

She was ordered Tuesday  to spend an additional 18 months under house detention, for allowing an American, John Yettaw, to stay at her home,  after he swam there uninvited in May.  

United Nations Secretary-General Ban Ki-moon joined the U.S., Britain, and France in condemning the ruling.  Thursday, the U.N. Security Council issued a statement, expressing  "serious concern" about the situation. The non-binding statement called on Burma to immediately release Aung San Suu Kyi and  other political prisoners, and begin a genuine dialogue with the Nobel Peace Prize laureate.

British Ambassador John Sawers says, "If the government of Myanmar (Burma) want their process to have international credibility, they know what they have to do."

Walter Lohman is  the director of Asian studies at the Heritage Foundation. He says China - a Security Council member with close ties to Burma - will never allow tough U.N. sanctions against Burma.

Lohman says the Association of Southeast Asian Nations, known as ASEAN,  represents the only hope in bringing change.

"You could try to at least put some pressure on the Chinese, at least call them out, on the issue of their arms exports," Lohman says. "They have exported between $2 and  $3 billion worth of arms to the Burmese. You could pressure their bank accounts abroad. You could get the ASEANs to come on board for sanctioning some of the investments that are made by the junta in Singapore and elsewhere."

Lohman says Indonesia could be a key player in exerting pressure on its neighbor. "Indonesia is the heart of ASEAN. Without Indonesia, there is no ASEAN. The Indonesians are much more vocal, much more concerned about this issue than anyone else in the region."

Meanwhile, a U.S. senator, Democrat Jim Webb of Virginia, has arrived in Burma to meet with its military leaders, as part of a five nation tour of Asia.