It 's a conflict culled from the suspicion-filled pages of the Cold War . Russia 's upper house of Parliament gives the green light for the incursion of military forces into Ukraine 's volatile Crimea region . President Vladimir Putin justifies the move as a necessary step to the protection of Russian citizens and military personnel in southern Crimea . Ukraine 's new government calls out what it calls Russia 's threat on its sovereignty . Map : A divided Ukraine . U.S. President Barack Obama warns of the `` costs '' Russia faces for its actions . With Ukraine possibly teetering on the brink of war , here are three things you need to know about the conflict . 1 . What is the Black Sea Fleet ? A justification for Russian might in the region is its claim of the need protect the Black Sea Fleet in the Ukraine . Based in Sevastopol , the force is the smallest of the Russian navy 's four fleets -- which once included some 18 submarines , two cruisers , 30 destroyers and frigates and around 100 smaller combat ships , according to Jane 's International Defense Review . Many vessels are aging and in need of maintenance . The Russian navy has had a base in Sevastopol for 230 years . The ships and subs are based just north of Turkey and can reach the Mediterranean . The fleet has been a point of contention since 1954 , when the former Soviet Union transferred the Crimea , including Sevastapol , to Ukraine , according to Jane 's . In 2010 , the two countries reached an agreement to permit the fleet to stay in Sevastopol until 2042 . Under the deal , Ukraine received a 30 % discount on the cost of natural gas supplies from Russia , potentially saving Ukraine up to between $ 40 billion over a10-year period . The fleet has allowed Moscow to exert its influence in the Eastern Mediterranean , Balkans and Middle East , according to Christian Le Miere , an expert at the International Institute for Strategic Studies . `` The importance of the Mediterranean to Russia was highlighted in 2013 , when , amid the civil war in Syria , Moscow declared the creation of a 'permanent task force ' for the sea and bolstered its presence to 10 vessels , '' he wrote . `` In August 2008 , it was the Black Sea Fleet that provided the 13 vessels used to defeat the small Georgian navy and land troops in Abkhazia and Poti during the brief war . '' 2 . How close is Russia to sending more troops ? According to the Russian state news agency Itar-Tass , the country 's constitution requires that the Federation Council must consider and debate the use armed forces outside Russia following a request from the president . The request should contain `` sound reasons '' for the use of the military . The chair of the council then sends the request to the upper house 's committee on defense and security and the committee on international relations . After the council considers the request , the president and the prime minister are invited to attend a council meeting , according to Itar-Tass . The meeting opens with a report delivered by the president or a representative . Then , the conclusions of the council committees on defense and security and international relations are read . A final decision on allowing the use of the armed forces outside the country must be adopted by a majority of the council members and and made formal in a resolution of the upper house , according to the news agency . The document is forwarded to the president within two days of its adoption . 3 . Is there a precedent for what might unfold ? In 2008 , Russia 's incursion into the former Soviet republic of Georgia followed the launch of a Georgian campaign against the Russian-backed separatist territory of South Ossetia . Russian tanks , troops and armored vehicles poured into South Ossetia and another breakaway Georgian territory , Abkhazia , advancing into Georgian cities across the administrative borders within those regions . The two sides blamed each other for starting the conflict , as well as for a wide variety of offenses leading up to and during the fighting , including ethnic cleansing . Russia and Georgia signed a French-brokered , six-point cease-fire agreement that allowed Russian forces to establish a buffer zone inside Georgia within a few kilometers of South Ossetia . What 's going Ukraine ? Crimea : 5 things to know .
Tensions are running high in Ukraine 's Crimea peninsula . Russian navy has had base at the city of Sevastopol for 230 years . The Ukrainian government is trying to take control of it, but Russia says they have no right and that all ships should leave port immediately.