Why did the USSR decide to also build an atomic bomb in 1949?

-So it's this event:

http://en.wikipedia.org/wiki/Soviet_atomic_bomb_project



So why did they do it? was it a statement of power or was it the result of something..

On the wikipedia page it said that Georgii Flerov's letter to Stalin led him to start a plan to build his own country's nuclear weapons.. but could i have further details of the significance of this? and does this correlate to the nuclear arms race?



Thanks so much!When the Americans built M.I.K.E (the fist thermonuclear explosive device), the Russians needed a form of retaliation which came also in the form of a nuclear device. Their 50 megaton 'Tsar' bomb far outdone the Americans with their 15 kiloton device. This sparked the cold war, the race for space and all subsequent events. Most people don't realise how close we came to omnicide 40 years ago.
The world at that time was divided between the capitalist countries and those ruled by Communism (and the so called Third World). The Communists saw themselves as being in an epic, ideological struggle with the West, but the capitalists (US and allies) had bombs and the Communists did not.



The wikipedia page for the Cold War may be more helpful.
The USA had the bomb. Their greatest enemy the USSR didn't. So to give the country security against an attack from the USA they had to get it, (even though the technology was stolen from the USA). The outcome is protection designated MAD (mutually assured destruction), and that's why there have been no more wars in Europe.
Stalin blockaded Berlin in 1948. The city was within the Soviet zone, although subject to the control of all four major powers. The Soviets cut off all rail and road routes to West Berlin. Convinced that he could starve and freeze West Berlin into submission, no trucks or trains were allowed entry into the city. However, this decision backfired when Truman embarked on a highly visible move that would humiliate the Soviets internationally鈥攕upplying the beleaguered city by air. Military confrontation threatened while Truman, with British help, flew supplies over East Germany into West Berlin during the 1948鈥?9 blockade. This costly aerial supplying of West Berlin became known as the Berlin Airlift.



Truman joined eleven other nations in 1949 to form the North Atlantic Treaty Organisation (NATO), the United States' first "entangling" European alliance in 170 years. Stalin replied to these moves by integrating the economies of Eastern Europe in his version of the Marshall Plan, exploding the first Soviet atomic device in 1949, signing an alliance with Communist China in February 1950, and forming the Warsaw Pact, Eastern Europe's counterpart to NATO.
Soviets had always consider USA their enemy. Even during WW2 Marx doctrine of the world domination as a goal did not change. USA stood right on the road to achieve this goal.



It was a long established 40,000 years long tradition not allow your enemy to have better weapons than you have. It would be very strange if USSR would not want nuclear bomb from the moment USA had one.



You could see the very same tradition at work when India and Pakistan both had developed nukes.

You can see the very same tradition at work as Saudi Arabia is going yo have a nuclear weapons because Iran practically got them recently.