CANNES, France I’m always afraid of being attacked physically,” Lars von Trier half-joked in response to a journalist who wondered if the great Dane feared fisticuffs at the press conference for “Manderlay,” the second film in the director’s USA trilogy after “Dogville” (which premiered at Cannes 2003). The concerned reporter was referring to possible retaliation for Mr. von Trier’s role as professional provocateur, one who’s come under attack, particularly by American critics, for making “anti-American” screeds.

The fact that the flying-phobic Mr. von Trier has never set foot in the States enrages his detractors even further. But the director offered an explanation: “America is now sitting on the world. Sixty percent of my life is America, so in fact I am an American. But I can’t go there to vote to change things. That’s why I make films about America.”

“Dogville” is perhaps the most incendiary, trenchant look at the American ethos ever committed to screen, a tale of how charity and piety can all too quickly give way to exploitation and bloodlust. Set in 1933,”Manderlay” follows Grace, “Dogville’s” heroine, to an Alabama plantation where slavery still exists almost 70 years after the end of the Civil War. Although smart and caustic at times, the new film often sags, and its provocations about racism are rarely able to sustain their sting.

Several people sitting near me in the balcony of the Grand Theatre Lumiere walked out during yesterday morning’s press screening; those who stayed for the credits offered perfunctory applause, as though they were congratulating themselves for enduring Mr. von Trier’s 139-minute lecture (“Dogville’s” three hours, in contrast, fly by with never a dull moment).

Part of the problem may be that “Manderlay” repeats the same structure as that of its predecessor: Both films are set on nearly bare soundstages, are divided into chapters, feature John Hurt’s mordant narration, and conclude with David Bowie’s “Young Americans” and a series of withering photos by Jacob Holdt. Yet what stood out as formally audacious in “Dogville” comes off as tedious the second time around.

When asked by a Brazilian journalist why he replicated this structure, Mr. von Trier replied with faux sheepishness, “I have a way of punishing myself. One of the ways is to make three films the same way. I thought that would be mature. I admire directors who do the same thing again and again and do it better. Maybe I’m not that type – but I’m trying to be.”

The two films also star two different Graces of vastly different talent. “Dogville” would be only smart agitprop without Nicole Kidman’s astonishingly brave performance as a Depression-era Sister Christian turned Pirate Jenny. Kidman had originally signed on to play Grace in all three USA films but had to drop out because of scheduling conflicts. Her replacement in “Manderlay” is the eager but inadequate 24-year-old Bryce Dallas Howard (daughter of Ron).

Queried by a reporter from Australia about working with Mr. von Trier again, Ms. Howard replied with clipped solemnity, “I would amputate my toes to work with Lars again. And that’s not really an exaggeration, honestly.” As for how she felt about replacing Ms. Kidman, the young actress responded, with a slight hint of defensiveness, “Of course I was enchanted by ‘Dogville’ and watched it several times because of how impressed I was by the film and how impressed I was with Nicole’s performance specifically. But I didn’t try to do any kind of mimicry.”

Perhaps the real provocateur at the “Manderlay” press conference was Danny Glover, who plays an old house slave named Wilhelm. Wearing a T-shirt that read “Kick Ass Artists,” Mr. Glover bounced from Brown v. Board of Education to UNESCO to Martin Luther King to pronouncements about “art elevating the human experience” in his garrulous responses, almost all of which were met with applause. No journalist clapped, however, when Mr. Glover smiled and said, “If we were really talking about the right questions, a lot of you wouldn’t have jobs.”