Will China's new fentanyl controls make a difference?

China is adding new restrictions on 13 chemicals that are used to make the synthetic opioid behind most overdose deaths in the United States. The move stems from a recent Trump-Xi agreement and is meant to curb the flow of precursors from China to Mexico, where cartels produce most of the illegal fentanyl entering the US. But experts say the impact may be limited: Traffickers adapt quickly, many ingredients remain unregulated and new suppliers - like India - could easily step in. The World's Tibisay Zea reports from Mexico City.