Israel has become a world leader in science on the medical uses of marijuana, and its producers could become major exporters of medical cannabis. But so far, the government has allowed them to export only their knowledge — not the actual product. Michael Dor, the senior medical adviser in the Israeli Health Ministry’s cannabis unit, said that in ongoing government talks, agricultural officials support the export of Israeli medical cannabis, but top officials in the police force, army and executive branch oppose it. Exports face stringent international legal requirements.