When the United States involves itself militarily in a conflict, it often finds it hard to get itself out, let alone avoid deep entanglements that blow well past lines it had drawn at the start of the intervention.
It happened in Vietnam, when U.S. military advisers helping the South Vietnamese fight Viet Cong eventually became U.S. soldiers fighting an American war. It happened in Afghanistan, when an initial invasion to capture al-Qaida and overthrow the Taliban morphed into a nearly two- decade-long nation-building project. And it could be happening right now in Ukraine.