This comes a day after a senior administration official told reporters that the US and Iran are close to a deal requiring Iran to relinquish its uranium, which has been enriched to near-bomb grade. Iran has escalated efforts to seal off its stockpile of enriched uranium, collapsing tunnels, and placing explosive mines at entrances in recent weeks, CNN reported on Saturday, citing five sources familiar with US intelligence. This comes a day afte... [1875 chars]