The USA is a leading member of a number of important international organisations.
These groups contain most of the countries in the world with the largest economies. Summits or meetings of the leaders of the G8 countries offer the opportunity for the US and other group members to develop closer economic ties to expand trade. In addition, it allows the US another forum to discuss issues of global concern such as climate change, terrorism or conflict and poverty. In 2014, Russian membership of the G8 was suspended because of its involvement in the crisis in Ukraine.
The G20 has similar aims to the G8 but includes an additional 12 members to reflect the growing economic importance of countries such as Brazil, India and Indonesia.
The USA is a founding member of the United Nations (UN):
Although the US is an important member of the UN, the relationship between the two has been strained. The US hosts the UN headquarters in New York and contributes the most of any single country to UN programs but in most years the US has failed to pay its contribution in full.
As a permanent member of the UN Security Council, the US has the opportunity to veto any Security Council proposal put forward. Since the Security Council is the part of the UN responsible for peace making and peacekeeping as well as international sanctions, this gives the US a very influential role.
The US has at times found decision making within the UN Security Council frustrating or time consuming. Russia and China are also permanent members and often use their veto to block US proposals.
On occasion the US has ignored the UN and its decision-making procedures. For example, the US did not seek UN approval when it decided to invade Iraq in 2003. The US has also consistently backed Israeli actions financially and militarily despite widespread UN and international condemnation.
Like many other countries, the US will do what it believes is in its best interests regardless of what the UN or the rest of the world think. However, on most occasions, the US does work within the decision-making processes of the UN Security Council, e.g. leading a response to the crisis in Libya in 2011. More recently, the USA's diplomatic efforts have lead to resolving issues in Syria.
The US has been a member of the North Atlantic Treaty Organisation (NATO) since it was established in 1949. NATO is the largest and most powerful military alliance in the world. In theory, the 28-nation organisation is made up of members of equal standing, where each country has one vote in decision making.
In recent years, the USA has also tried to encourage the other members of NATO to take a greater responsibility for their own defence and to make a larger contribution to NATO's finances. It has been argued that the US has been focusing its attention more towards Asia and the Far East as opposed to Europe. However, with Russian annexation of the Crimea in 2014, NATO and American support for the Atlantic Alliance has moved close to the top of the US international agenda.
US leadership within NATO remains very important. For example, in terms of the NATO involvement in Libya in 2011, American military support was crucial in securing the downfall of Libyan President Gaddafi. The USA also played the lead role in NATO's mission to Afghanistan. However, the US also needs NATO as it allows the US to confront difficult and diverse threats to its security alongside other countries which support democratic values. As part of NATO the US is stronger.