Radicalism is rising in North America. The large and varied late April protests throughout the continent against the Free Trade Area of the Americas (FTAA) confirmed, if there was any doubt, that this anti-capitalist, pro-democracy movement of many movements continues to grow. There's creative ferment everywhere, and the greatest sense of radical possibility in a generation.

For parts of the American global justice movement, the exposure and connection that the FTAA protests brought to Canada's more freewheeling direct-action tradition are greatly accelerating the move toward more militant tactics that began when the anarchist Black Bloc went window-smashing during the late 1999 World Trade Organization meetings in Seattle. These two dynamics – a broad sense of momentum and growth, and an increasingly combative culture of street protest – give this moment a feeling of promise, unpredictability, and peril. It's a time of great excitement, daring acts, much serious organizing, and some very stupid posturing.

I spent late April in Quebec City, where the leaders of 34 Western Hemispheric nations were meeting, in a charming walled city made sinister by the addition of another man-made wall, guarded by phalanxes of faceless police in riot gear. There an estimated 50,000 demonstrators were barraged with nearly 5000 canisters of tear gas, in two days of stunning street confrontations that greatly eclipsed Seattle in intensity.

Simultaneously, thousands of protesters in dozens of places – from the Tijuana-San Diego border to El Paso to Kansas City – were answering the call to "localize the movement for global justice" by holding rallies, marches, and direct actions that made connections between pressing issues in their communities and the sweeping trade pact being negotiated in Quebec City. These were also a response to widespread critiques of "summit-hopping," the post-Seattle activist trend of jumping from one mega-mobilization to the next.

In both its lead-up and its realization, Quebec City felt like a turning point. Two of the main groups calling for the protest, the Anti-Capitalist Convergence and the sardonically named Welcoming Committee for the Summit of the Americas – familiarly known by their French acronyms, CLAC and CASA – announced from the start that they would organize on the basis of "respect for a diversity of tactics." Specifically, they committed not to renounce "violence" (always a slippery term) or to denounce any demonstrators' methods of dissent.

For Canada, this stance wasn't out of line with past radical direct actions, although CLAC and CASA's position did stir up a lot of controversy in the weeks and months before the Summit. For Americans, though, this kind of tactical carte blanche has been virtually unheard of at large-scale protests since the street-fighting days of the late 1960s. Beginning with the anti-nuclear movement of the mid-1970s, it's been standard procedure at most mass actions in the United States to have nonviolence codes, explicit agreements about the limits of acceptable behavior that all participants are asked to respect. They have varied in intensity and scope. Some codes have been incredibly sweeping, prohibiting even angry speech, while others have been more limited, mainly proscribing physical violence against people (including police).

One of the hallmarks of the direct-action anti-globalization movement in the United States has been its growing unease with these traditional rules. It's not that there's been a mass embrace of street combat or property destruction among American radicals, although interest in those tactics is clearly growing among a small but highly visible group. Instead, there seems to be a broadening consensus against denouncing people who do those things, a reluctance to draw lines between "good" and "bad" protesters, and a recognition that the overwhelming majority of the violence to date has come from the police.

In Quebec City, outrage at the hated wall and the vicious tear gassing quickly overwhelmed much lingering ambivalence about the "diversity of tactics" approach. When armed thugs are barraging you with chemical weapons simply because you've gathered to oppose the secret negotiations of a tiny elite, it's hard to get real worked up about whether folks should be throwing rocks at them or not. Don't get me wrong: I strongly disagree with some things that Black Blocers did in Quebec, particularly the use of Molotov cocktails. But out there in the streets, under attack, the atmosphere was one of almost total unity.

From moment to moment, you felt you were in the midst of a fireworks display, a sporting event, or a war zone. A low thwomping sound announced the discharge of each gas canister, and you looked up at the sky to trace its arcing path and gauge how close to you it would land. There's a delay then before the noxious chemicals are actually released, and in those crucial seconds, the crowd would wait to see if someone – usually a Black Blocer wearing thick gloves – would pick up the superheated thing and hurl it back at the cops. Often, someone would, and a huge cheer would go up as you saw the trail of gas head toward the police line. Or, if not, a thick toxic cloud would begin to spread; some folks would panic, but others always urged the crowd to stay calm. There would be cries for medics to wash out the burning eyes of the unprotected – the movement medics were flat-out amazing, selfless and superbly prepared – and before long, you'd hear the French chant that became the watchword for the action: "So – so – so – solidarité!"

This scene repeated itself countless times, most movingly for me on Saturday evening, the second and larger of the two big days of protest. My buddy Mark and I joined a crowd of perhaps a few thousand engaged in one of these standoffs on an elevated ramp of the Dufferin-Montmorency Highway, which juts out from a high cliff that the police were seeking to clear of protesters. The gassing was relentless: canister after canister of the foul stuff, sometimes so much of it you could hardly see. But the more they shot at us, the more it made people want to stay. Mark and I had mediocre goggles but great masks – the kind painters use when working with solvents – so we were pretty well protected, but all around us were people with nothing more than vinegar-soaked scarves around their faces, coughing and crying but still chanting their solidarity and standing firm.

Suspended in air, we all held our surreal ground as best we could, but inevitably we were pushed slowly down the ramp, as the riot squads advanced and blanketed us with poison. When it comes down to brute force, after all, the state will always win. But below, underneath the freeway's concrete tangle, was L'Îlot Fleurie, a longtime sculpture and community garden that served as a kind of staging ground for the protests. Mark and I had been there earlier – it was, among other things, where Food Not Bombs was serving up free meals to all comers – but as we descended we saw that the place was now packed with thousands and thousands of bedraggled, euphoric veterans of the weekend's battles. People were creating art, sharing food, providing first aid, building bonfires, and making music – astonishing music, for their instrument was the freeway itself, its guard rails and light posts transformed into the biggest, most sonorous drum set you ever heard. We threw down our packs and joined the joyous rave, dancing beyond all fatigue. Up on the cliff you could see the glint of streetlights on the face shields of the riot cops, and it made us smile: Sure, they had walled us out and pushed us down, but it had only brought us all more strongly together, and that counted as victory.

In certain radical circles back in the States, though, the militant acts at the front lines are being seen – and celebrated – in isolation, as part of a growing mystique of insurrection. Check out the collage poster of FTAA photos assembled by the Barricada Collective, a Boston-based anarchist group that has been influential in promoting Black Bloc actions. It features image after image of young men in the throes of battle – tossing a gas canister, waving a red flag, pushing down the fence, wielding a big stick, lifting a barricade – with the yeah-right tag-line, "against the violence of capitalism and the state." Perhaps one or more of the costumed figures is a woman, but I doubt it (even though there are plenty of women Black Blocers). You don't see any of the medics in the poster, or the folks who supplied us with food, or the camaraderie of L'Îlot Fleurie. You see anger and adrenaline, but you don't see solidarity.

Meanwhile, I'm hearing more and more loose talk about dangerous things: someone saying there should be "lots more violence" in the movement; others talking up the idea of armed struggle; jokes about explosives that leave a sense of unease. And I wonder if all the folks who are moving toward greater militancy have really thought through the possible consequences. Given the government's posture to date toward the global justice movement, and the Black Bloc in particular, I think it we could soon see people doing serious jail time for things that happen during demonstrations.

A call is already circulating for a "diversity of tactics" Black Bloc at the next big summit action, outside the Washington, D.C. meetings of the International Monetary Fund and World Bank in early October. It reads, in part, "We will not be content with reforming, or even abolishing the IMF/World Bank. We will not rest until every last bank has been burned, till the last memory of banks has been erased from our world."

I find this hyperbole more humorous than menacing. But it brings me back to the debate about summit-hopping, and why it's a problem for the movement. New York-based activist Lesley Wood says, rightly I think, that major mobilizations and local organizing don't have to be seen as antithetical to one another, assuming people are involved in both: Big actions like Seattle or Quebec City inspire and energize people in ways that can directly or indirectly benefit community-based campaigns when they return to their home towns.

Radicals whose activism largely consists of mobilizing for one big action after another, however, tend to develop very different politics from those who are deeply enmeshed in local organizing. There's a kind of rigor to nuts-and-bolts campaigning with concrete, immediate stakes – say, fighting to stop a power plant from being built in a low-income neighborhood with epidemic asthma rates – that privileges strategy over gestures. Without that grounding, it's all too easy to make the great militant error of elevating tactics to principles, rather than seeing them as tools, and to engage in confrontation for its own sake.

But even as I worry about a creeping recklessness that's likelier to fuck people up than fuck shit up, it's clear that the audacity of the Black Bloc is an electric charge – and it's getting people juiced. CLAC has a slogan: "It didn't start in Seattle, and it won't end in Quebec City." Look for things to intensify.