2. Reasons the Cold War started
In today’s class I am learning to:
• Describe weapons developments in
the years following World War Two
• Analyse the impact of these
weapons in causing the Cold War
3. Reasons the Cold War started
During World War Two,
all major countries
were involved in
trying to develop
atomic weapons.
The USA set up a
secret organisation
called the Manhattan
Project to try
successfully create a
working atomic bomb.
4. Reasons the Cold War started
In July 1945, the USA
was finally successful
in making a working
atomic bomb.
The ‘Trinity’ test
took place in a desert
in New Mexico. An
successful explosion
took place with the
power of 22 kilotons
of TNT.
5. Reasons the Cold War started
The USA then chose to
use their new weapon
on Japan.
On 6 August 1945, an
atomic bomb nicknamed
‘Little boy’ was
dropped on Hiroshima
Three days later, ‘Fat
man’ was dropped on
Nagasaki.
6. Reasons the Cold War started
The results of these
new weapons were
devastating. Up to
250,000 people died
due to the blasts, and
possibly more in
future years.
As a result of this,
Japan surrendered on
14 August 1945. This
ended World War Two.
7. Reasons the Cold War started
Although the USA and
USSR were allies, the
USA did not tell the
USSR about their plans
to use the weapon
(although Stalin
already knew due to
Soviet spies).
The USA also refused
to share their new
technology.
8. Reasons the Cold War started
The USA’s decision to
use the weapon without
telling the Soviets –
and also to share the
technology – proved to
the USSR that the USA
could not be trusted.
The Soviets even
worried that the USA
planned to attack them
with the bombs.
9. Reasons the Cold War started
However Americans were
tired of war; the USA
had no plans to attack
the USSR.
The USA had in fact
provided lots of
support to the Soviets
during WW2, including
13,000 combat vehicles
and 4.5 million tonnes
of food.
10. Reasons the Cold War started
The main reason the
USA used the bombs on
Japan was to end the
war more quickly.
America believed if
they invaded Japan
that more people would
die (including US
soldiers). The use of
bombs aimed to stop
the need for invasion.
11. Reasons the Cold War started
In April 1949, a
military alliance
called North Atlantic
Treaty Organisation
(NATO) was set up.
12 countries –
including the USA, UK,
Italy and France –
committed to protect
each other if any one
country was attacked.
12. Reasons the Cold War started
The Soviets still
wanted atomic weapons.
In August 1949 they
finally developed
their own working
atomic bomb.
Some of this was
achieved due to spies
in America who passed
nuclear secrets to the
Soviet Union.
13. Reasons the Cold War started
Now that both sides had
atomic bombs, there was
huge tension.
In Western Europe, US-
supporting countries
worried that they might
be attacked by the
Soviet Union. They
wanted the protection
of NATO to stop this.
14. Reasons the Cold War started
The establishment of
NATO was clear
evidence to the USSR
that the USA did not
trust them.
Other Soviets worried
that America was
planning an attack on
the USSR, and building
an army for this.
15. Reasons the Cold War started
However in 1949 the
Soviet Union knew that
they were close to
building their atomic
own bomb (which they
achieved in August
that year).
They knew that the USA
was not likely to
attack them, limiting
this issue’s impact.
16. Reasons the Cold War started
The Soviet Union later
established their own
military alliance – the
Warsaw Pact.
This was set up in May
1955 and included
members such as the
Soviet Union, Albania,
Bulgaria, East Germany
and Czechoslovakia.
17. Reasons the Cold War started
The fact that both
sides now had their
own military alliance
increased tensions and
fears between them.
This made the prospect
of conflict much more
likely, and thus
helped develop the
Cold War.
18. Reasons the Cold War started
However each side
argued that their
military alliance was
only defensive – it
was not intended to
attack the enemy.
As long as neither
side launched an
attack on the other,
there was no need for
conflict or war.
19. Reasons the Cold War started
Once both sides had
atomic bombs, they
continued to try to
develop bigger and
more powerful weapons.
In 1952, the USA first
made a powerful
hydrogen bomb; the
Soviet Union did the
same in 1953.
20. Reasons the Cold War started
Hydrogen bombs were
even more powerful
than atomic bombs.
The USA’s Castle Bravo
test at Bikini Atoll
in 1954 was a powerful
blast, around 15,000
kilotons.
This compares to 15
kilotons at Hiroshima.
21. Reasons the Cold War started
The Soviet Union later
created the most
powerful bomb ever
exploded – the Tsar
Bomba.
In October 1961, the
USSR’s bomb exploded
with a power of 50,000
kilotons. The blast
was carried out in the
far north of the USSR.
23. Reasons the Cold War started
The top of the
explosion cloud from
the Tsar Bomba was 40
miles high.
It vaporised
everything within a 36
mile radius. However
the damage extended to
a radius of 150 miles,
with windows shattered
as far away as Norway.
25. Reasons the Cold War started
The ongoing growth of
nuclear weapons
created tensions
between the sides.
This made it more
likely that one side
might use their
weapons, especially if
they believed they had
an advantage over the
other.
26. Reasons the Cold War started
However some people
argue these
developments stopped
the possibility of
war because neither
side could risk using
the weapons without
fear of retaliation.
This is known as
‘Mutually Assured
Destruction’.