US-Iran war LIVE updates: Iran intensified its attacks on Friday as air raid sirens were heard in many parts of West Asia, including Bahrain and Israel, amid the war entering its 21st day.

The United States has weakened Iran’s military capabilities. However, Iran continues to fire missiles and drones at its neighbors and U.S. military sites, which shows the country has maintained its ability to strike militarily.

Here is a look at the country’s power structure, what is known — and what is not. Ultimate authority in Iran rests with the country’s supreme leader, who has sat at the apex of power since the creation of the Islamic Republic in 1979 after the revolution that overthrew the shah.

The U.S. is increasing its military presence in the Middle East amid escalating threats from Iran, which has vowed to compromise safety in global tourist destinations. The conflict has resulted in significant casualties and disruptions in the energy market.

Securing the Strait of Hormuz could mean deploying U.S. troops to Iran's shoreline, said four sources, including two U.S. officials.

The war in Iran cost about $16.5 billion within its first 12 days. At that rate, an extra $200 billion could potentially fund the war through mid-August.

Even as Iran confronts the gravest threat to its regime yet, it is signaling a willingness to prolong its conflict with the United States and Israel in a bid to finally reshape the region in its favor.

Sri Lanka did not agree to the request, officials said, and has tried to remain neutral in the U.S.-Israeli war in Iran.

Bases on U.S. soil shut down after reports of active shooters and suspicious packages. Some have banned uniforms off base.