Angelina Jolie gave a slight smile to photographers as she walked through Heathrow Airport in London today. The stop was just a layover on her journey from LA to Pakistan, which she is visiting as part of her role as a UN goodwill ambassador. She recently recorded a PSA about the flood disaster in the country, calling attention to the devastated area. Before heading off on her latest humanitarian mission, Angelina brought Knox and Vivienne to say hi to Brad Pitt on the set of Moneyball. The twins also got to come along for Angelina's last time abroad, and their four older kids joined her in Asia in July and the Bay Area last month, though this time her trip isn't doubling as a family vacation too.