President Obama is joining other world leaders in Germany today as the G7 summit comes to a close. Heads of state are holding talks in a secluded resort inside a 100-year-old castle. Outside the summit, protesters have been met by a massive show of police force, with as many as 20,000 officers deployed. Thousands of demonstrators took to the streets Saturday in the nearby town of Garmisch. On Sunday, leaders and reporters had to be shuttled to the G7 talks by helicopter after protesters blocked a main road. Issues under discussion include climate change, austerity, Greece’s fiscal crisis, the Trans-Pacific Partnership trade deal, and what President Obama called “Russian aggression” in Ukraine.