The recognition that a follow-on treaty would not be signed before START expired becomes evident. There was also the recognition that high-level engagement was required to induce progress in the negotiations. Chairman Mullen traveled to Geneva to meet Makarov for this purpose. Little advancement occurred. The verification procedures remain the most significant impediment. START expired on December 5, 2009. The two sides remained optimistic but as the holiday season approached, the negotiators recognized that intervention at the presidential level was required. Obama and Medvedev met in Copenhagen in mid-December during a climate change summit. They achieved some agreement, but also acknowledged that an agreement would not be forthcoming quickly. Mullen and Makarov agreed to meet in Moscow in late January 2010 to help move the process along.