In Jan. 1999, Nazarbayev was sworn into office for another seven years, although the election was widely criticized when an opposition leader was disqualified on a technicality. Despite his authoritarianism, Nazarbayev, who has ruled Kazakhstan since 1989 (when it was still part of the Soviet Union), is a widely popular leader. Kazakhstan has the potential for becoming one of central Asia's richest countries because of its huge mineral and oil resources and its liberalized economy, which encourages Western investment. In 2000, oil was discovered in Kazakhstan's portion of the Caspian Sea. It is believed to be the largest oil find in 30 years. In March 2001, a pipeline opened to transport oil from the Tengiz fields to the Russian Black Sea port of Novorossiysk. In 2004, Kazakhstan signed a deal allowing China to build an oil pipeline to the Chinese border.