These scenes run counter to Buddhism's philosophy of shunning politics and embracing even bitter enemies - something the faith has adhered to, with some tumultuous exceptions, through its 2,500-year history.
But political activism and occasional eruptions of violence have become increasingly common in Asia's Buddhist societies as they variously struggle against foreign domination, oppressive regimes, social injustice and environmental destruction.
More monks and nuns are moving out of their monasteries and into slums and rice paddies - and sometimes into streets filled with tear gas and gunfire.
"In modern times, preaching is not enough. Monks must act to improve society, to remove evil," says Samdhong Rinpoche, prime minister of the Tibetan government-in-exile and a high-ranking lama.
"There is the responsibility of every individual, monks and lay people, to act for the betterment of society," he told The Associated Press in Dharmsala, India, discussing protests in Tibet this month that were initiated by monks.
In widespread protests over the past three weeks, crimson-robed monks - some charging helmeted troops and throwing rocks - have joined with ordinary citizens who unfurled Tibetan flags and demanded independence from China. Beijing's official death toll from the rioting in Lhasa is 22, but the exiled government of the Dalai Lama says 140 Tibetans were killed there and in Tibetan communities in western China.
Bloodshed also stained last fall's pro-democracy uprising in Myanmar, dubbed the "Saffron Revolution" after the color of the robes of monks who led nonviolent protests against the country's oppressive military regime.
In Thailand, followers of a Buddhist sect took part in street demonstrations which led to the ouster of Prime Minister Thaksin Shinawatra two years ago.
In Sri Lanka, the ultra-nationalist Jathika Hela Urumaya party, led by monks, has pushed for using brute force against the country's Tamil rebels. In 1959 a monk assassinated a prime minister over a law giving some protection to the Tamil language.
Indeed, the activism reflects another side of Buddhist history. Despite the faith's image of passivity, an aggressive strain has long existed, especially in the Mahayana school of Buddhism, practiced in Japan, Korea, China and Tibet.
The sohei, monks in Japan, fought pitched battles with one another and with secular clans for over 600 years until around 1600. China's Shaolin Temple, a martial arts center to this day, was allowed to retain warrior monks from the 7th century by emperors who sometimes used them to put down rebellions and banditry.
The monk Saya San became a national hero in the 1930s in Myanmar - then Burma - by leading a revolt. The British colonials hanged him after fielding 12,000 troops to suppress his peasant army.
The self-immolation of monk Thich Quang Duc on a Saigon street became an iconic image of protest against the Vietnam War.
Before China's takeover of Tibet in 1959, warrior monks sometimes wielded more power - and weaponry - than the army. Lhasa's Sera monastery, a hotbed of the recent protests, was particularly noted for its elite fighters, the "Dob-Dobs," who in 1947 took part in a rebellion that took 300 lives.
"Use peaceful means where they are appropriate, but where they are not appropriate, do not hesitate to resort to more forceful means," said the previous, now deceased Dalai Lama when Tibet fought the Chinese in the 1930s.
Christopher Queen, an expert on Buddhism at Harvard University, says the new trend among some of the world's 350 million faithful is expanding from individual spiritual liberation to attacking problems such as poverty and environmental blight that affect whole communities or nations.
Sri Lanka's Sarvodaya Shramadana, or "Mundane Awakening," provides everything from safe drinking water to basic housing in more than 11,000 poor villages. And in India, Buddhist groups are fighting for the rights of "the untouchables," the lowest caste.
Global and loosely affiliated, originating at the grass roots rather than atop religious hierarchies and more muscular than meditative, this movement is widely known as Engaged Buddhism.
"Engaged Buddhists are looking at the social, economic, and political causes of human misery in the world and organizing to address them. The role of social service and activism is clearly growing in all parts of the Buddhist world," Queen said in an interview.
While not immune to spilling blood, Queen says "the Buddhist tradition is rightly known for the systematic practice of nonviolence." That leads scholars to doubt it will turn to terrorism or sustained violence other than occasional spontaneous outbursts. They note that Buddhism doesn't advocate killing heretics or otherwise spreading the faith by force.
Indeed, the Dalai Lama has decried the recent violence while supporting peoples' rights to peaceful protest. And Samdhong, the prime minister-in-exile, adds: "If (monks) want to fight, they have to disrobe and join the fighters."
Associated Press writers Anita Chang in Beijing, Ben Stocking in Hanoi, Ambika Ahuja in Bangkok, Burt Herman in Seoul, Gavin Rabinowitz in Dharmsala and Ravi Nessman in Colombo contributed to this report