Question: On what day did the country where Rigatta is from become part of the Soviet Union?

full_context: Document 1: Estonia: In 1989, during the "Singing Revolution", in a landmark demonstration for more independence, more than two million people formed a human chain stretching through Lithuania, Latvia and Estonia, called the Baltic Way. All three nations had similar experiences of occupation and similar aspirations for regaining independence. The Estonian Sovereignty Declaration was issued on 16 November 1988. On 20 August 1991, Estonia declared formal independence during the Soviet military coup attempt in Moscow, reconstituting the pre-1940 state. The Soviet Union recognised the independence of Estonia on 6 September 1991. The first country to diplomatically recognise Estonia's reclaimed independence was Iceland. The last units of the Russian army left on 31 August 1994.
Document 2: Molotov–Ribbentrop Pact: In mid-June 1940, when international attention was focused on the German invasion of France, Soviet NKVD troops raided border posts in Lithuania, Estonia and Latvia. State administrations were liquidated and replaced by Soviet cadres, in which 34,250 Latvians, 75,000 Lithuanians and almost 60,000 Estonians were deported or killed. Elections were held with single pro-Soviet candidates listed for many positions, with resulting peoples assemblies immediately requesting admission into the USSR, which was granted by the Soviet Union. The USSR annexed the whole of Lithuania, including the Scheschupe area, which was to be given to Germany.
Document 3: Communications in Somalia: As of 2009, dial up, wireless and satellite services were available. Dial up internet services in Somalia were among the fastest growing on the continent, with an annual landline growth rate of over 12.5%. The increase in usage was largely due to innovative policy initiatives adopted by the various Somali telecom operators, including free local in-town calls, a flat rate of $10 per month for unlimited calls, a low charge of $0.005 per minute for Internet connections, and a one-time connection fee of $50. Global Internet Company, a firm jointly owned by the major Somali telecommunication networks Hormuud Telecom, Telcom Somalia and Nationlink, was the country's largest ISP. It was at the time the only provider of dial up services in Somalia's south-central regions. In the northern Puntland and Somaliland regions, online networks offered internet dial up services to their own group of subscribers. Among these firms was Golis Telecom Somalia in the northeast and Telesom in the northwest.
Document 4: Communications in Somalia: After the start of the civil war, various new telecommunications companies began to spring up in the country and competed to provide missing infrastructure. Somalia now offers some of the most technologically advanced and competitively priced telecommunications and internet services in the world. Funded by Somali entrepreneurs and backed by expertise from China, Korea and Europe, these nascent telecommunications firms offer affordable mobile phone and internet services that are not available in many other parts of the continent. Customers can conduct money transfers (such as through the popular Dahabshiil) and other banking activities via mobile phones, as well as easily gain wireless Internet access.
Document 5: Rigatta: Rigatta SIA is a licensed Latvian telecommunications company that provides telephony and network support services in the Baltic states and Frankfurt. Rigatta provides call-by-call, prepaid/postpaid, IP telephony, VoIP telephony, network and also the automatic dialer and network services.
Document 6: Forticom: Forticom is an IT company based in Latvia. It was the owner of online social networks One.lv (Latvian) and One.lt (Lithuanian). 100% of Forticom is owned by Mail.ru Group. At this moment the company sold one.lt but the second project one.lv was closed in January 2013.
Document 7: History of Latvia: The First Latvian National Awakening began in the 1850s and continued to bear fruit after World War I when, after two years of struggle in the Latvian War of Independence, Latvia finally won sovereign independence, as recognised by Soviet Russia in 1920 and by the international community in 1921. The Constitution of Latvia was adopted in 1922. Political instability and effects of the Great Depression led to the May 15, 1934 coup d'état by Prime Minister Kārlis Ulmanis. Latvia's independence was interrupted in June -- July 1940, when the country was occupied and incorporated into the Soviet Union. In 1941 it was invaded and occupied by Nazi Germany, then reconquered by the Soviets in 1944 -- 45.
Document 8: Communications in Somalia: After forming partnerships with multinational corporations such as Sprint, ITT and Telenor, these firms now offer the cheapest and clearest phone calls in Africa. These Somali telecommunication companies also provide services to every city, town and hamlet in Somalia. There are presently around 25 mainlines per 1,000 persons, and the local availability of telephone lines (tele-density) is higher than in neighboring countries; three times greater than in adjacent Ethiopia. Prominent Somali telecommunications companies include Somtel Network, Golis Telecom Group, Hormuud Telecom, Somafone, Nationlink, Netco, Telcom and Somali Telecom Group. Hormuud Telecom alone grosses about $40 million a year. Despite their rivalry, several of these companies signed an interconnectivity deal in 2005 that allows them to set prices, maintain and expand their networks, and ensure that competition does not get out of control.
Document 9: Nexcom Bulgaria: Nexcom Bulgaria, LLC is a licensed telecommunications operator, founded in 1998. The company is 100% owned by the US Nexcom Telecommunications, LLC, one of the first operators in the world, developing the Voice over Internet protocol technology (VoIP). Nexcom is the first operator in Bulgaria, providing products and services, based on the VoIP technology. Prior to selling its wholesale operations in 2003, Nexcom was the leading alternative telecommunications provider in 12 countries throughout Central and Eastern Europe. Nexcom designed, developed and operated the first pan-regional facilities based VoIP provider in the world. The company developed a seamless retail and corporate internet telephony solution more than five years before the launch of Skype.
Document 10: Sudatel: Sudatel is a telecommunications and Internet service provider in the Sudan. The company is responsible for the construction and maintenance of Sudan's telecom infrastructure. Sudatel is more than 60% owned by the Sudanese government; the remainder being owned by private interests. Its stock is listed on the Bahrain Stock Exchange.
Document 11: Latvian Soviet Socialist Republic: Following the Welles Declaration of July 23, 1940, the annexation of Latvia into the Soviet Union (USSR) on 5 August 1940 was not recognized as legitimate by the United States, the European Community, and recognition of it as the nominal fifteenth constituent republic of the USSR was withheld for five decades. Its territory was subsequently conquered by Nazi Germany in June -- July 1941, before being retaken by the Soviets in 1944 -- 1945. Nevertheless, Latvia continued to exist as a de jure independent country with a number of countries continued to recognize Latvian diplomats and consuls who still functioned in the name of their former governments.
Document 12: Estonia: On 6 August 1940, Estonia was annexed by the Soviet Union as the Estonian SSR. The provisions in the Estonian constitution requiring a popular referendum to decide on joining a supra-national body were ignored. Instead the vote to join the Soviet Union was taken by those elected in the elections held the previous month. Additionally those who had failed to do their "political duty" of voting Estonia into the USSR, specifically those who had failed to have their passports stamped for voting, were condemned to death by Soviet tribunals. The repressions followed with the mass deportations carried out by the Soviets in Estonia on 14 June 1941. Many of the country's political and intellectual leaders were killed or deported to remote areas of the USSR by the Soviet authorities in 1940–1941. Repressive actions were also taken against thousands of ordinary people.
Document 13: Dissolution of the Soviet Union: On June 14, 1987, about 5,000 people gathered again at Freedom Monument in Riga, and laid flowers to commemorate the anniversary of Stalin's mass deportation of Latvians in 1941. This was the first large demonstration in the Baltic republics to commemorate the anniversary of an event contrary to official Soviet history. The authorities did not crack down on demonstrators, which encouraged more and larger demonstrations throughout the Baltic States. The next major anniversary after the August 23 Molotov Pact demonstration was on November 18, the date of Latvia’s independence in 1918. On November 18, 1987, hundreds of police and civilian militiamen cordoned off the central square to prevent any demonstration at Freedom Monument, but thousands lined the streets of Riga in silent protest regardless.
Document 14: Central African Republic: Presently, the Central African Republic has active television services, radio stations, internet service providers, and mobile phone carriers; Socatel is the leading provider for both internet and mobile phone access throughout the country. The primary governmental regulating bodies of telecommunications are the Ministère des Postes and Télécommunications et des Nouvelles Technologies. In addition, the Central African Republic receives international support on telecommunication related operations from ITU Telecommunication Development Sector (ITU-D) within the International Telecommunication Union to improve infrastructure.
Document 15: Post-Soviet states: The post-Soviet states, also collectively known as the former Soviet Union (FSU) or former Soviet Republics, are the 15 independent states that emerged from the Union of Soviet Socialist Republics in its dissolution in December 1991, with Russia internationally recognised as the successor state to the Soviet Union. On March 11, 1990, Lithuania was the first to declare its independence, with Estonia and Latvia following suit in August 1991. All three Baltic states claimed continuity from the original states that existed prior to their annexation by the Soviet Union in 1944 and were admitted to the United Nations on 17 September 1991. The remaining 12 republics all subsequently seceded. 12 of the 15 states, excluding the Baltic states, initially formed the CIS and most joined CSTO, while the Baltic states focused on European Union and NATO membership.
ground_truth: 5 August 1940
sub_queries: Rigatta >> country Answer: Latvia
when did Latvia become part of the soviet union Answer: 5 August 1940