U.S. Senator John McCain was back in Arizona on Monday to begin treatment for brain cancer, but his situation did not stop him from again slamming the Trump administration for having “no strategy for success in Afghanistan” more than six months after the presidential inauguration. “When the Senate takes up the National Defense Authorization Act in September, I will offer an amendment based on the advice of some our best military leaders that will provide a strategy for success in achieving America’s national interests in Afghanistan,” McCain, chairman of the Senate Armed Services Committee, said in a statement released Monday. “Eight years of a ‘don’t lose’ strategy has cost us lives and treasure in Afghanistan,” the Republican added. “Our troops deserve better.” Defense Secretary James Mattis had promised to deliver to Congress a strategy by mid-July, yet no finished strategy has materialized. The administration is still debating a plan that …