Newsbeat's guide to... the United Nations
There is growing pressure on Syria after a massacre that killed dozens of children.
The United Nations (UN) says the attack on the town of Houla was an "outrageous act of force".
Kofi Annan, who helped sort out the ceasefire deal, is now heading back to the country for talks with Syria's president Bashar al-Assad.
One hundred and eight people were killed in total with 300 more injured.
Syria's UN envoy condemned what he called a "tsunami of lies" being told by some members of the UN Council, saying Syrian forces were not to blame.
Find out what the UN is and what powers it has to stop violence around the world.
Formation and aims
The United Nations is an organisation that was formed after the end of the Second World War by the US, UK, USSR (Russia) and China.
It took over from the League of Nations, which had been established after the First World War.
It is designed to keep peace and security for people around the world and promote friendly relations between countries.
The UN now has 193 members - The Vatican and Taiwan remain outside the organisation.
All member countries, which make up the General Assembly, contribute towards the costs of running the UN, although the organisation is owed billions of pounds by member states.
UN Security Council
The UK is a member of the United Nations but is also a core member of the organisation.
The UN's Security Council comprises China, UK, US, France and Russia.
Ten other countries have a rotating membership - India, Germany, Japan and Brazil want to be made permanent members.
The council can impose economic sanctions, authorise the use of force and looks after peacekeeping operations.
If one of the five permanent members disagrees with a decision (or resolution), it can veto the action and it can't be passed.
An example of this is Russia and China vetoing a Security Council resolution calling on the Syrian government to stop attacking civilians.
It did however authorise a no-fly-zone over Libya last year.
The UN Charter also aims to protect people's human rights.
States are also required to work together to combat social, economic, humanitarian and cultural problems.
The main groups within the UN are the Economic and Social Council, the International Court of Justice based in The Hague and the Secretariat, which does the day to day work of the UN.
The United Nations also has 14 independent agencies including the International Atomic Energy Agency (IAEA), Children's Fund (Unicef) and the World Food Programme based in Rome.