By Alina Selyukh WASHINGTON (Reuters) – The top U.S. telecom regulator on Thursday asked phone, cable and other companies to step up and show measurable actions they take to protect communications networks from cyber attacks and hold themselves accountable without new regulations. In his first major speech devoted fully to cybersecurity, Federal Communications Commission Chairman Tom Wheeler urged the private sector to step up to assume new responsibility and market accountability for managing cyber risks before the FCC takes a regulatory approach to the problem. The private sector-led effort must be more dynamic than traditional regulation and more measurably effective than blindly trusting the market or voluntary best practices to defend our country, Wheeler said in a speech at the American Enterprise Institute, a public policy group. We believe in a new regulatory paradigm where the commission relies on industry and the market first while preserving other options if that approach is unsuccessful. Improving protections of U.S. critical infrastructure like communications networks and the electric grid has been a priority for the Obama administration, but security experts continue to worry about the reluctance of many corporate leaders to spend more money on improving defenses.