Countries have gone to war for less. Air pollution from forest fires in Indonesia has choked its neighbors for months, but politically, the regional response has been relatively benign.
And the Association of Southeast Asian Nations (ASEAN) can probably take the blame, or credit.
"The nature of engagement on this issue has very much been following the non-interference, non-confrontational norms of the organization," Helena Varkkey, a senior lecturer for the Department of International and Strategic Studies at the University of Malaya, told CNBC via email. "The nature of ASEAN also is that most sensitive issues are discussed off-the-record (corridor or coffee-break diplomacy)," she added.
"Under ASEAN norms, it would seem that it is more important to keep Indonesia 'on side' (not to offend or overtly pressure Indonesia), with resolving the problem more of a secondary concern," she said.
That may be a factor in the recurring, annual nature of the forest fires, which are deliberately set in Indonesia's rainforests to clear land, generally to produce palm oil and paper products.
Another factor is that ownership of the companies involved in the burning can cross borders.
"Commercial plantations, many of which have Malaysian and Singaporean links, have been found to be a major source of these fires," Varkkey said, adding it blurs the lines between "culprit and victim."
For example, Asia Pulp & Paper (APP) is controlled by Indonesian conglomerate Sinarmas Group, itself controlled by the Widjaja family, which also has Singapore-listed palm-oil player Golden Agri-Resources under its umbrella.
Under the Transboundary Haze Pollution Act, Singapore's government required APP to submit information about its Indonesian suppliers and fire-fighting efforts; APP has said it has a "no burning" policy, but conceded to the Straits Times last month that there have been fires on suppliers' land. That doesn't prove who started them, the company added.
This year, a lack of rain and an El Nino weather system has meant the air pollution caused by the fires, colloquially called "the haze," has been particularly severe and long-lived this year, covering Southeast Asia in air pollution. That's caused cancellations of flights in Thailand, Singapore, Malaysia and the Philippines, as well as forcing some schools to close. Singapore's air quality began to worsen in August and first entered unhealthy levels in September.