Up until the World Wars the United States had not taken part of to many wars that occurred on a global scale. After these efforts the United States began to take on the role of global police and continues this role. This has led to US involvement in the Cold War, Vietnam War, and the Korean War. The most recent wars in which we have involved ourselves in are the war in Afghanistan and the war in Iraq.
The US was rightful in declaring war on Afghanistan because of the terrorist attacks that occurred on September 11th 2001. The United States had the backing of its allies from the United Nations and this led to a speedy success in the sense that the US was able to take down the Taliban regime with the increased troops due there ally backing. The US then made the mistake of leaving Afghanistan before it had help to set up a new government and ensure the Afghans were able to protect themselves. By withdrawing prematurely the United States threatened the sovereignty of Afghanistan and the countries surrounding it. Now that the US has increased its activity in Afghanistan once again they must make sure that a stable government is set up and this government must be able to rule within its borders or the US will inevitably have to become involved again.
The US was not right when the invaded Iraq because they did so without probable cause and the without the backing of their allies in the United Nations that would have led to a faster success and less US casualties. The US did do the right thing by ensuring they had helped to set up a stable Iraqi government and that this government was able to defend themselves and their people from harmful outside influences such as the Taliban.
Therefore moving forward the United States should continue its global police role and refrain from taking military action if they do not have the backing of their allies. But, the US should take action if they are provoked in some sort of way by terrorist or a country in general. If the Taliban or North Korea were to attack the US should take immediate action to prevent further harm of Americans. However, the United States should not take on an imperialistic role and start invading countries because the use of goods and raw materials from these potential colonies could benefit the US economy.