The United States are the world's leading power in economic, political and military terms.
After an economic slowdown following the 2008 financial crisis, the US managed to recover; and today it experiences a solid economic growth. Its GDP remains the largest in the world. America is also a major hub of scientific research and technological innovation; and (contrarily to most advanced economies) it has a favorable demographic outlook. Moreover, it has become an exporter of hydrocarbons thanks to the exploitation of shale gas and oil, thus dramatically reducing its dependence on energy imports and bringing significant benefits to its own economy; even though this has also raised environmental concerns.
The US military is a large, powerful and well-trained armed force equipped with high-tech weapon systems that can be deployed virtually anywhere in the world. The US also enjoys an advantageous geographic position: because it is naturally protected by two oceans (which also mean it can easily project its power overseas) and has no hostile powers along its borders. At the same time, America has military bases all over the world and possesses an unmatched power projection capability; especially thanks to its naval supremacy. Because of this, the US is the main security provider that ensures the free access to the global commons. Finally, the US holds a vast and advanced nuclear arsenal for strategic deterrence.
As a result, America is the most influential power on Earth, and is the cornerstone of the current international order. Today's international law and institutions (notably the United Nations) were inspired and sustained by the US. Washington also has key allies in every region, who benefit from its protection and enable its forces to operate across the whole planet.
However, America's supremacy is being challenged. In particular, the rise of China is making it more difficult for the US to freely exert its power and influence. Russia is alos a near-peer competitor that counter's its geopolitical primacy. Iran and North Korea also create stategic problems, albeit to a more limited scale. Moreover, being the world's first power, America must face challenges in every region of the globe; and properly balancing the different (and often conflicting) interests and values is a difficult endeavor. More than any other state, the US face the risk of imperial overstretching: gradually losing its economic vitality and consequently its power due to a rise in military expenditures and the need to ensure an armed presence in too many places, which also implies the danger of being involved in costly conflicts overseas.
Finally, the US has also its own share of domestic problems to face. The social tensions on issues such as the condition of black people, the sanitary and education systems, income inequality and others will affect America's role in the world; and climate change will also have a major impact on its economy and on its committment abroad by creating new security challenges.