Palestinian minister Ziad Abu Ein (L) scuffles with an Israeli border policeman near the West Bank city of Ramallah, Dec. 10, 2014. (REUTERS/Mohamad Torokman)

It's a tragic irony: the senior Palestinian minister who died following an incident with Israeli security forces was an official associated with non-violent protests in the West Bank against Israeli land grabs.

Ziad Abu Ein, 55, died on Wednesday in circumstances that are still murky, as my colleagues William Booth and Ruth Eglash report. Attending a demonstration at the West Bank village of Turmus Aya, he got involved in a scuffle with Israeli border police, inhaled tear gas and likely succumbed to a heart attack. Witness reports suggest he had been jostled and struck by armed police.

Following international calls for a transparent and swift investigation, Israeli authorities say they are looking into the matter.

"What happened today is an intolerable crime in every sense of the word," said an angry Palestinian President Mahmoud Abbas, who also called his colleague's death a "barbaric act."

Abu Ein was with a group of non-violent marchers waving Palestinian flags and carry saplings of olive trees in this village not far from the city of Ramallah. They planned to plant the trees on soil near the Jewish settlement of Shiloh, land they fear Israel plans to annex. Among the contingent were activists from an Israeli human rights group that was petitioning the country's Supreme Court to remove the nearby unauthorized Israeli outpost of Adei Ad.

The Israeli military says it deployed its forces to "halt the progress of the rioters" -- the term it chose to apply to the protesters.

This protest march is part of a larger, longstanding struggle. In the wake of the second Intifada a decade ago, many Palestinians in the West Bank, a territory under Israeli military occupation, have watched as Israel has built a "separation barrier" through their lands and expanded Jewish settlements, which are deemed illegal under international law.

In myriad small villages dotting the territory, Palestinians have protested their dispossession with similar "non-violent" marches, which, when intercepted by Israeli forces, sometimes escalate into skirmishes between stone-throwing Palestinians and fully-armed Israeli soldiers, firing tear gas canisters and more lethal ammunition. Clashes have also broken out between protesters and settlers.

The 2013 Oscar-nominated documentary "5 Broken Cameras" (see the trailer above) spotlighted the village of Bil'in, where weekly non-violent marches toward Israeli barriers built through Palestinian farmland started in 2005 and grabbed worldwide attention. In the tradition of civil disobedience elsewhere, the Bil'in protesters don't seem to know when to quit -- even when, as in the case with Abu Ein, they face death.

I wrote about the film's emotional arc last year:

5 Broken Cameras hammers into the viewer an endless, jarring loop of asymmetric violence. The Palestinians of Bil’in squat on what was once their farmland and approach en masse a boundary fence that they believe shouldn’t exist only to be met by tear gas and gunshots. Many are arrested and wounded. The cycle repeats itself over and over again, captured by [local filmmaker Emad] Burnat’s five broken cameras. The most climactic moment of the film is when an unarmed Bassem Abu-Rahmah—a handsome, charismatic man known as “el-Pheel,” or the elephant, for his broad shoulders and “child’s heart”— dies after a tear gas canister fired at close range hits him in the chest. Bil’in’s collective grief thereafter is palpable. “With all this despair around, Emad just keeps going on and on,” says [the documentary's Israeli co-director Guy] Davidi. “It’s a story of resistance.”

For quite some time, officials of the Palestinian Authority were kept at arms-length from these acts of "resistance" -- to some villagers, they represented an institution that operated hand-in-glove with the Israeli occupiers. But in recent years, Abbas's largely toothless government has taken a more active role in joining the protests. Last March, then Palestinian prime minister Salam Fayyad had to be evacuated from Bil'in after Israeli troops fired tear gas into crowds of protesters.

Abu Ein spent time decades ago in Israeli and American prisons for his role in terrorist plots. But, as a minister without portfolio in Abbas's government, he came to champion the popular protests against Israeli settlements and outposts.

Israeli authorities justify their tough response to these protests on grounds of security. But this form of dissent is a moral universe away from the militant activity, terror strikes and rocket attacks that Israel's government usually points to when inveighing against Palestinian perfidy.

The Israelis "don’t want this type of struggle because if there is a non-violent movement it will weaken the occupation," Issa Amro, a Palestinian activist, told Israeli news site +972 magazine on Wednesday. "They say the occupation is there for security, but if the struggle is non-violent then they can no longer justify the occupation."

Gabi Lasky, a leftist Israeli attorney who defends human rights activists and is also Tel Aviv city council member, says the protests serve as an illustration of how "the security forces defend the settlers and land thieves" and ignore Palestinian grievances.

“Instead of ending the injustice they try and curb and prevent non-violent protests," Lasky tells +972. "In doing so, the security forces use violence against anyone who attempts to realize their most legitimate right — to protest. That’s what happened here. And this time, like in previous incidents, it ended with death.”