Markwayne Mullin, the new DHS secretary, has said he is considering cuts to customs agents at international airports in US cities that do not cooperate with his department's deportation efforts. Kent NISHIMURA / AFP via Getty Images The head of the DHS says he wants to punish sanctuary cities by limiting customs processing at certain airports. That sparks a lot of questions. And industry watchers say it would unleash massive travel chaos. A major airline trade group and the administration's tra