By JENNIFER H. SVAN | STARS AND STRIPES Published: May 12, 2021 KAISERSLAUTERN, Germany — The Air Force acknowledged that the display by security forces airmen at Ramstein Air Base of a “thin blue line” flag violated Defense Department policy on what types of flags can be flown on U.S. bases. The 86th Airlift Wing posted and later removed photos on its Facebook page of airmen in uniform carrying a black-and-white American flag with a blue horizontal stripe during a 24-hour rucksack march as part of National Police Week. The photos drew immediate condemnation by some in the community who questioned the display on a U.S. military base of a flag that has become a polarizing symbol in a nation grappling with police violence and racism.