YANGON In recent years, disputes over maritime claims in the South China Sea have been the main cause of discord within the Association of Southeast Asian Nations. But a different kind of threat to regional cooperation has emerged from the ongoing tragedy in Myanmar's western Rakhine State.

Myanmar and Malaysia, both ASEAN members, have been at loggerheads over Rakhine since early October, when Muslim Rohingya militants stormed border posts along Myanmar's border with Bangladesh, killing nine policemen and seizing weapons caches. Myanmar's security forces subsequently launched a brutal counterinsurgency campaign that has driven nearly 70,000 Rohingya refugees into neighboring Bangladesh and displaced at least 23,000 more, according to United Nations agencies. As of early February, at least 600 Muslims were detained in northern Rakhine -- mainly in military camps -- on suspicion of aiding terrorism.

A Feb. 3 report by the U.N. Human Rights Council featured harrowing accounts by Rohingya refugees in Bangladesh of army abuses in northern Rakhine, including the gang rape of women and murder of children.

In response to the report, Myanmar's government, which is led by State Counselor Aung San Suu Kyi, initially softened its prior outright denials of military abuse and promised to investigate the allegations. But on Feb. 7, it said it needed more information from the U.N.

Naypyitaw's earlier denials had prompted criticism from around the world. On Jan. 20, Yanghee Lee, the U.N. human rights envoy to Myanmar, said: "For the government to continue being defensive when allegations of serious human rights violations are persistently reported, that is when the government appears less and less credible."

Previously, Myanmar railed against a meeting of the Organization of Islamic Cooperation on the Rohingya crisis, held in Malaysia on Jan. 19, during which Malaysian Prime Minister Najib Razak reiterated harsh criticisms of Naypyitaw's policies, saying: "The killing must stop, the burning of houses must stop, the violation of women and girls must stop." He had earlier urged international intervention in Myanmar and accused the government of "genocide" against the Rohingya.

In response, Myanmar's foreign ministry accused the OIC's 57 member states of ignoring the October border attack and what it claimed were the government's "genuine efforts" to address the issue. It added: "There is no attempt to persecute a community on grounds of religion."

The ministry, headed by Suu Kyi, said the sensitive issue was being "exploited to promote a certain political agenda," and suggested that Najib was rallying Malaysia's majority Muslim community in efforts to distract voters from corruption allegations ahead of elections due by 2018.

"Najib is doing everything he can to deflect from the 1MDB issue," said Melissa Crouch, a law lecturer at the University of New South Wales who specializes in Southeast Asian religion and politics. 1MDB is a Malaysian state fund from which the prime minister is accused of siphoning off around $700 million.

Since losing the popular vote -- but not his hold on power -- in elections in 2013, Najib has also been courting Malaysia's main Islamist party, which fought the election as part of an opposition coalition. The OIC meeting followed a public rally staged by Najib on Dec. 4 in Kuala Lumpur to support the Rohingya, when he said: "The world cannot sit by and watch genocide taking place."

ROCKING THE BOAT Regardless of Najib's motives, Malaysian pressure on Myanmar has undermined one of ASEAN's key principles -- noninterference in the internal affairs of other member states. Najib's defense, as he explained to the OIC meeting, was that "if the domestic affairs of a country result in instability which affects other countries in the region, they cannot be expected to remain silent."

Whether Najib's broadsides change how ASEAN members assess each other's internal politics remains unclear. Asked about the dispute between Myanmar and Malaysia after publication of the Feb. 3 U.N. report, Phay Siphan, a Cambodian government spokesman, said: "According to the principles of ASEAN, we don't interfere. Both Myanmar and Malaysia are friends of Cambodia."

In practice, ASEAN's noninterference principle has meant that member states are rarely criticized or questioned about human rights or governance issues -- including the 2014 military coup in Thailand, Vietnam's imprisonment of advocates of free elections and the Philippines' war on drugs.

Indeed, after Myanmar joined ASEAN in 1997, the noninterference principle translated into scant official support for Suu Kyi, who spent a total of about 15 years under house arrest up to 2010. Similarly, ASEAN stayed silent about the thousands of political prisoners held under Myanmar's military junta before limited liberalization in 2011. The NLD took power after a sweeping election victory in 2015.

Now, Suu Kyi's government in Myanmar sees noninterference as a defense against outside criticism of its actions in Rakhine State.

"We need to maintain good relations between the countries but, noninterference ... is part of ASEAN, and the Rakhine State issue is only one of many issues facing ASEAN," government spokesman Zaw Htay said.

Most of the country's estimated 1.1 million-plus Rohingya population is denied citizenship by a 1982 law and have been subject to communal violence, particularly since 2012. The Rohingya were subsequently told they would be included in Myanmar's 2014 census only if they agreed to be called "Bengali," a label that suggests they are immigrants from Bangladesh.

Until Najib's recent criticisms, the Rohingya were largely ignored by Muslim-majority ASEAN member states such as Indonesia and Malaysia, and generally by the Muslim world. Indonesia and Malaysia both tried to push back boatloads of Rohingya refugees during another recent crisis in 2015.

"The Rohingya issue [has] been there since decades," said Maszlee Malik of the International Islamic University of Malaysia, noting that even during Malaysia's recent one-year term as ASEAN chair, and its temporary seat on the U.N. Security Council, government's response "was not really substantive."

"True, the international interest is exclusively focused on the citizenship issue and humanitarian hardships of Muslim Rohingyas," said Jacques Leider, an author and expert on Rakhine issues. "Yet the bitter irony ... is that hundreds of thousands of Muslim migrants who identify as Rohingya have lived in OIC member countries -- most prominently in Saudi-Arabia and Bangladesh -- for decades without ever enjoying much OIC support, with little Muslim solidarity and being rarely offered a track to apply for citizenship despite living there for generations."

"MEGAPHONE DIPLOMACY" Malaysia hosts an estimated 56,000 Rohingya refugees and hundreds of thousands more Myanmar migrant workers, and therefore has a vital interest in solving the Rakhine crisis. However, Najib's verbal attacks on Naypyitaw, have been criticized, at least implicitly, by Indonesia.

On Nov. 25, 2016, protestors in Jakarta decried the brutal crackdown by Myanmar's army on Rohingya in northern Rakhine State. (Photo by Simon Roughneen)

Visiting Myanmar straight after the OIC meeting, Indonesian Foreign Minister Retno Marsudi told media that "megaphone diplomacy" and "naming and shaming" would not achieve a "doable solution" to the Rohingya problem -- an indication, perhaps, that ASEAN's biggest member state wants to stop the Malaysia-Myanmar dispute from widening.

But street protests across Asia in December -- including in Jakarta and Kuala Lumpur -- saw an outpouring of anger against Myanmar, and, in Jakarta, an attempt to elide Buddhist-majority Myanmar's treatment of the Rohingya with an alleged disparagement of Islam by leaders of Indonesia's ethnic Chinese minority.

More valid are concerns that Myanmar's military campaign in Rakhine State could inflame Indonesians and Malaysians who have fought for or sympathize with the Islamic State terrorist movement in Iraq and Syria.

That could fuel a violent backlash among Muslims in Malaysia and Indonesia, giving both countries urgent reasons to seek resolution of the Rakhine conflict. Police in both countries have arrested people said to have been targeting the Myanmar Embassy in Jakarta or planning to carry out attacks in Myanmar.

Against this background, the upcoming ASEAN summit in the Philippines in late April is likely to feature both Malaysian megaphone diplomacy and Indonesian importuning on the Rohingya issue -- with the prospect of wider acrimony if other member countries are dragged reluctantly into the politics of Rakhine State. With increasing international uncertainty amid Donald Trump's tumultuous first weeks as U.S. president, one thing is clear: ASEAN could do without a divisive internal squabble.