Question: when did the country Skrunda-1 is located become part of the Soviet Union?

full_context: Document 1: 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 2: Anti-aircraft warfare: From the early 1930s eight countries developed radar, these developments were sufficiently advanced by the late 1930s for development work on sound locating acoustic devices to be generally halted, although equipment was retained. Furthermore, in Britain the volunteer Observer Corps formed in 1925 provided a network of observation posts to report hostile aircraft flying over Britain. Initially radar was used for airspace surveillance to detect approaching hostile aircraft. However, the German Würzburg radar was capable of providing data suitable for controlling AA guns and the British AA No 1 Mk 1 GL radar was designed to be used on AA gun positions.
Document 3: 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 4: 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 5: 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 6: 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 7: 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 8: Saint Helena: A satellite ground station with a 7.6-metre (25 ft) satellite dish installed in 1989 at The Briars is the only international connection providing satellite links through Intelsat 707 to Ascension island and the United Kingdom. Since all international telephone and internet communications are relying on this single satellite link both internet and telephone service are subject to sun outages.
Document 9: Estonia: Militarization was another aspect of the Soviet state. Large parts of the country, especially the coastal areas, were closed to all but the Soviet military. Most of the sea shore and all sea islands (including Saaremaa and Hiiumaa) were declared "border zones". People not actually residing there were restricted from travelling to them without a permit. A notable closed military installation was the city of Paldiski, which was entirely closed to all public access. The city had a support base for the Soviet Baltic Fleet's submarines and several large military bases, including a nuclear submarine training centre complete with a full-scale model of a nuclear submarine with working nuclear reactors. The Paldiski reactors building passed into Estonian control in 1994 after the last Russian troops left the country. Immigration was another effect of Soviet occupation. Hundreds of thousands of migrants were relocated to Estonia from other parts of the Soviet Union to assist industrialisation and militarisation, contributing an increase of about half a million people within 45 years.
Document 10: 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.
Document 11: Skrunda-1: Skrunda-1, also known as Skrunda-2, is a ghost town and former Soviet radar station located 5 km (3 mi) to the north of Skrunda, in Raņķi Parish, Latvia. It was the site of two Dnepr radar (NATO "Hen House") radar installations constructed in the 1960s. A Daryal radar was being built there before the collapse of the Soviet Union. Skrunda was strategically important to the Soviet Union as its radars covered Western Europe. The two barn-like radars were one of the most important Soviet early warning radar stations for listening to objects in space and for tracking possible incoming ICBMs.
Document 12: Sputnik 1: Sputnik 1 (/ ˈspʊtnɪk / or / ˈspʌtnɪk /; ``Satellite - 1 '', or`` PS - 1'', Простейший Спутник - 1 or Prosteyshiy Sputnik - 1, ``Elementary Satellite 1 '') was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957, orbiting for three weeks before its batteries died, then silently for two more months before falling back into the atmosphere. It was a 58 cm (23 in) diameter polished metal sphere, with four external radio antennas to broadcast radio pulses. Its radio signal was easily detectable even by radio amateurs, and the 65 ° inclination and duration of its orbit made its flight path cover virtually the entire inhabited Earth. This surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the Cold War. The launch ushered in new political, military, technological, and scientific developments.
Document 13: Pechora Radar Station: Pechora Radar Station () is an early warning radar near Pechora in the Komi Republic, northern Russia. It is a key part of the Russian early warning system against missile attack and was built by the Soviet Union, becoming operational in 1984. It is run by the Russian Aerospace Defence Forces.
Document 14: Lithuanian Soviet Socialist Republic: The Lithuanian Soviet Socialist Republic (Lithuanian SSR; Lithuanian: Lietuvos Tarybų Socialistinė Respublika; Russian: Литовская Советская Социалистическая Республика, Litovskaya Sovetskaya Sotsialisticheskaya Respublika), also known as Soviet Lithuania or Lithuania was a republic of the Soviet Union. It existed from 1940 to 1990.
Document 15: Scud: Scud is the name of a series of tactical ballistic missiles developed by the Soviet Union during the Cold War. It was exported widely to both Second and Third World countries. The term comes from the NATO reporting name attached to the missile by Western intelligence agencies. The Russian names for the missile are the R-11 (the first version), and the R-17 (later R-300) Elbrus (later developments). The name Scud has been widely used to refer to these missiles and the wide variety of derivative variants developed in other countries based on the Soviet design.
ground_truth: 5 August 1940
sub_queries: Skrunda-1 >> country Answer: Latvia
when did Latvia become part of the soviet union Answer: 5 August 1940