Mitchell's "new Srebrenica" line echoes Jan Egeland, the United Nations official who's responsible for trying to broker humanitarian access in Syria. The effectiveness - or otherwise - of UN efforts to deliver aid into Syria has been one of the many vexed issues of this crisis. With Srebrenica (as with Rwanda) the UN failed abysmally. Is it going to fail with Syria as well? Let's fervently hope not. And let's hope that Aleppo stays at the centre of international attention. Because, even without a standalone massacre of Srebrenica's magnitude, Aleppo is already a frightening humanitarian emergency. Aleppo isn't the new Srebrenica, it's the old Aleppo. And that's easily bad enough.