and disposition of the former Soviet Black Sea Fleet that helped to reduce tensions. However, Ukraine cut diplomatic relations with Russia as a response to the Russian invasion of Ukraine. Ukraine became a (non-official) member of the Commonwealth of Independent States (CIS) on December 8, 1991. In January 1993 it refused to endorse a draft charter strengthening political, economic, and defense ties among CIS members, and completely ceased to participate as a member in March 2014. Ukraine was a founding member of GUAM (Georgia-Ukraine-Azerbaijan-Moldova). In 1999–2001, Ukraine served as a non-permanent member of the UN Security Council. Soviet Ukraine joined the United Nations in 1945 as one of the original members following a Western compromise with the Soviet Union, which had asked for seats for all 15 of its union republics. Ukraine has consistently supported peaceful, negotiated settlements to disputes. It has participated in the quadripartite talks on the conflict in Moldova and promoted a peaceful resolution to conflict in the post-Soviet state of Georgia. Ukraine also has made a substantial contribution to UN peacekeeping operations since 1992. Leonid Derkach (chairman of the SBU, which is Ukraine's security service, successor to the KGB) was fired due to Western pressure after he organized the sale of radar systems to Iraq while such sales were embargoed. International disputes Belarus The 1997 boundary treaty with Belarus remains un-ratified due to unresolved financial claims, stalling demarcation and reducing border security. Russia Delimitation of the land boundary with Russia is incomplete, but the parties have agreed to defer demarcation. The maritime boundary through the Sea of Azov and the Kerch Strait remains unresolved despite a December 2003 framework agreement and on-going expert-level discussions. Prime Minister Vladimir Putin allegedly declared at a NATO-Russia summit in 2008 that if Ukraine would join NATO his country can contend to annex the Ukrainian East and Crimea , Now in 2023 Russia has already annexed the Crimean peninsula and Four regions of Ukraine, Donetsk, Luhansk, Kherson and Zaporizhzhia . Starting in November 2013, the decision by Ukrainian President Viktor Yanukovych to back out of signing an integration agreement with the European Union started a period of civil unrest between Ukrainians who favored integration with the European Union and those who wanted closer ties with Russia. This culminated in the Revolution of Dignity. Russia took advantage of this political instability to annex Crimea in March 2014, though Ukraine still claims sovereignty