kqed's monica lam spoke with ai weiwei when he was in san ancisco. massive human migration due to war, violence, disaster. what did you learn from making is film? -what i have learned is very simple. amonthere's no single onegees, is willing to leave their home. they all struggle not to leave. it's very heavy price they have to pay. their relatives, friends, or whole village vanished by war, by famine, or environmental problems. -united states president lfdonald trump has cut in in fact, more than half the number of refugees allowed in ts country. what is your reaction to that? -i think that this current administration, what they did is beyond belief. -more than ever, we need the wall. we have drugs pouring through. -i should say it's a shame for a nation like ited states, which is the most powerful, not only leading in the economics but should be strongant nation in defending hights. after all, u.s. is a nation of immigrants. just a few generations ago, we all come from somewhere. er-absolutely. -i nevet a native here. i mean, to limit somebody's ri