Russia and Kazakhstan started a closer energy co-operation in 1998, which was further consolidated in May 2002, when Presidents Vladimir Putin and Nursultan Nazarbayev signed a protocol dividing three gas fields – Kurmangazy, Tsentralnoye, and Khvalynskoye – on an equal basis. Following the ratification of bilateral treaties, Russia, Kazakhstan and Azerbaijan declared that the northern Caspian was open for business and investment as they had reached a consensus on the legal status of the basin. Iran and Turkmenistan refused however to recognise the validity of these bilateral agreements; Iran is rejecting any bilateral agreement to divide the Caspian. On the other hand, US' choices in the region (within the framework of the so-called "pipeline diplomacy"), such as the strong support of the Baku pipeline (the project was eventually approved and was completed in 2005), reflect a political desire to avoid both Russia and Iran.