BRUSSELS — Enemies could exploit Europe’s fossil fuel dependence to “choke” the bloc in the event of a war, the European Union’s defense and climate chiefs warn.  The EU buys 95 percent of the oil and 85 percent of the natural gas its households, transport and industry consume from abroad. The European Commission and military officials are concerned this reliance on imports could become a security threat in times of conflict. That makes the bloc’s shift to clean, homegrown energy sources not