Afghanistan shooting: Leon Panetta flies in for surprise visit Panetta's visit coincides with a growing debate in Washington about the course of the 10-year-old war, with some sceptics in and outside the White House arguing for an accelerated drawdown of troops. Under current plans, the United States aims to reduce the force of nearly 90,000 to about 68,000 by the end of September, with most of the remaining combat troops due to be pulled out by the end of 2014. US officials have left the door open to a smaller follow-on force after 2014 but the spate of recent setbacks has complicated negotiations with the Afghan government for a long-term security agreement. On Monday, Panetta portrayed the shooting rampage as an isolated incident and insisted the US-led war effort was on track, with Taliban insurgents on the retreat. He told reporters that "we cannot allow these events to undermine our strategy or the mission that we're involved in." "It's important that we push on, and that we bring this war to a responsible end and achieve the mission that all of us are embarked on," he said. Karzai has described the massacre as "unforgivable," while US President Barack Obama on Tuesday said he had assured the Afghan president that "the United States takes this as seriously as if it was our own citizens and our own children who were murdered." Obama promised that the culprit would face the "full force" of US law, wherever the investigation led.