On the eve of the 2006 Riga summit, Senator Richard Lugar, head of the U.S. Senate's Foreign Relations Committee, declared that "the most likely source of armed conflict in the European theatre and the surrounding regions will be energy scarcity and manipulation." Since then, the variety of national policies and stances of larger exporters versus larger dependents of Russian natural gas, together with the segmentation of the European natural gas market, has become a prominent issue in European politics toward Russia, with significant geopolitical implications for economic and political ties between the EU and Russia. These ties have occasionally led to calls for greater European energy diversity, although such efforts are complicated by the fact that many European customers have long term legal contracts for gas deliveries despite the disputes, most of which stretch beyond 2025–2030. The EU's failure to successfully advance a common energy policy can be further exemplified by the building of the Nord Stream pipeline, which embodies the divisions between the center and the periphery of the EU—between Old and New Europe.