Trident: What is the UK's nuclear weapon programme?

The Vanguard, one of the Trident submarines

On 18 July MPs voted to renew the UK's nuclear weapon programme called Trident.

It's a big decision which will have an impact on the future of the UK.

The new Prime Minister Theresa May has said it would be a "gross irresponsibility" for the UK to abandon its nuclear weapons.

The Labour party is split over the decision, but their leader Jeremy Corbyn is against the renewal.

The Scottish National Party are opposed to renewing the Trident contract, it asked for the vote to be delayed to allow "proper scrutiny" but MPs voted to renew anyway.

A picture of a Trident missile test.

What is Trident?

Trident is the name of Britain's system of nuclear weapons - incredibly powerful bombs that can destroy whole cities on their own.

They also release huge amounts of radiation, which can cause horrible illnesses.

Nuclear weapons have only been used in war by one country. The US used two nuclear bombs in WWII against Japan - thousands of people died, and thousands more died later because of radiation sickness, caused by the bombs.

The American President at the time, Harry Truman, used them because he believed they would end the war sooner and so save many other lives.

Since 1969, according to government documents, a British submarine carrying nuclear weapons has always been on patrol, somewhere in the world's oceans.

Britain has four submarines in total.

The government says that the current Trident system will be out of date in the coming years, so a replacement is needed.

New Prime Minister Theresa May thinks Trident is a good idea.

What are the arguments FOR renewing Trident?

Government officials who support Trident say that it helps to protect the UK from other countries who might try to harm the UK.

Supporters of Trident say that the UK can prevent enemies from attacking just by having these destructive weapons, even if they are never used.

The nuclear defence industry employs a lot of people, and supporters say if the Trident programme isn't renewed, around 15,000 people could lose their jobs.

Campaigners against renewing Trident.

What are the arguments AGAINST renewing Trident?

Other people disagree with the UK owning nuclear bombs, as they think there is no justification for ever owning such destructive weapons.

They say that by getting rid of nuclear weapons, Britain would set a good example to others around the world.

Some people also think that Trident is very expensive - the project will cost the UK around £40 billion.

President Putin from Russia and President Obama from the US.

Do other countries have nuclear weapons?

The United States, Russia, the UK, France, China, North Korea, India, Pakistan all say they have nuclear weapons, and Israel is also believed to have them.

According to a report from the Stockholm International Peace Research Institute the nine countries share more than 15,000 nuclear weapons between them.

Russia and the United States own around 93% of these.

They have been asked by to reduce the number of weapons they have under a new agreement.

The UK is the only country which just uses submarines to deliver nuclear weapons.

Other countries like America use submarines and bombers, and France uses bombers as well as submarines.