Aphrodite gas field is an offshore gas field off the southern coast of Cyprus located at the exploratory drilling block 12 in the country's maritime Exclusive Economic Zone. Located 34 kilometres (21 mi) west of Israel's Leviathan gas field, block 12 is believed to hold 3.6 to 6 trillion cubic feet (100×10^9 to 170×10^9 m3) of natural gas. Noble Energy received the concession to explore block 12 in October 2008. In August 2011, Noble entered into a production-sharing agreement with the Cypriot government regarding the block's commercial development. Sources in Cyprus indicated in mid-September that Noble had commenced exploratory drilling of the block. Cyprus demarcated its maritime border with Egypt in 2003, and with Lebanon in 2007. Cyprus and Israel demarcated their maritime border in 2010. Turkey, which does not recognize the border agreements of Cyprus with its neighbors, threatened to mobilize its naval forces should Cyprus proceed with plans to begin drilling at Block 12. Cyprus's drilling efforts have the support of the United States, European Union, Russia and United Nations, and on September 19, 2011 drilling in Block 12 began without any incidents being reported. The development of oil and gas resources in the Cypriot Exclusive Economic Zone (EEZ) abide to the UN Convention of the Law of the Seas (UNCLOS) which the Republic of Cyprus ratified in 1988. The United Kingdom also has a claim on the area resulting from its sovereignty over two base areas in Cyprus. The treaty establishing the Republic of Cyprus (Annex I, Section III) specifically excluded any Cypriot claim to the two areas adjacent to the bases. For the Cyprus population the Aphrodite gas field can boost the local economy to counter rising unemployment. According to Noble Energy, a total gross unrisked deep oil potential is 3.7 billion barrels (590×10^6 m3). The field has a gross mean average of 7 trillion cubic feet (200 billion cubic metres) of natural gas with an estimated gross resource range of 5–8 trillion cubic feet (140×10^9–230×10^9 m3).