On 17 December, Ukraine signed a treaty with Russia under which Russia will buy $15 billion of Ukrainian Eurobonds and the cost of Russian natural gas supplied to Ukraine will be reduced, though Putin stated that "today we have not discussed the issue of Ukraine joining the ] at all". Three days later, high ranking EU-officials stated that the EU is still ready to sign the Association Agreement "as soon as Ukraine is ready for it", that the agreement was also beneficial for Russia and that the EU "is totally not concerned about the fact that Ukraine is signing agreements with Russia". On 23 December 2013 Russian presidential aide Yuri Ushakov stated "there is no contradiction" in Ukraine's association with the EU and their observer status in the Customs Union of Belarus, Kazakhstan, and Russia and the Eurasian Economic Union.