U.S. to end the Afghan war. Castro era ended in Cuba. Radioactive water to be discharged.

This week, we are drawing to a close on some of the most important chapters in history. And we may be about to open a disastrous one.

America's longest war about to end.

U.S. President Joe Biden announced that he is pulling all U.S. troops from Afghanistan on September 11 of this year. The United States first invaded Afghanistan on the eve of the 9/11 attack in 2001. After 20 years of war and at least 200,000 deaths across military and civilians, America's longest war will finally end (for the Americans).

Back in 2001, it was extremely emotional for Americans who witnessed the collapse of the Twin Towers. Most undoubtedly supported a ground invasion of Afghanistan. Yet perhaps few would have been able to point to a concrete next step once Osama Bin Laden is captured. In fact, many may simply have thought that the American troops can withdraw once the head of al-Qaeda is removed.

And the war could perhaps have been short. When the U.S. started bombing Afghanistan, the Taliban considered handing over, or at least, expelling Osama Bin Laden, in exchange for a ceasefire. It's impossible to tell now whether that was a genuine offer, but history may be very different if that happened. George W Bush's administration rejected the offer, and it took another ten years before Osama Bin Laden was killed by the U.S. armed forces in 2011.

What is for sure is that few Americans considered the possibility that the war would span over two decades, and even after two decades, a victory could not be achieved. Despite all the military gains, the Americans were never able to achieve their main objective of installing a functional civilian government in Afghanistan that will never play host to terrorist groups.

This, again, proves that it is easy to invade but difficult to govern, especially on foreign soil. Ahead of the country's parliamentary elections in 2018, less than 20% of the Afghans said they have confidence in the integrity of their elections. Under the current peace agreement, the Afghan government and the Taliban will agree to an untenable power-sharing. A bloodbath is likely to break out almost as soon as the Americans depart, which will again give terrorists a fertile ground for renewal.

From an Afghan’s perspective, the last twenty years were mostly marred by violence. After two decades of fighting and 200,000 lives lost, they could very soon be back at ground zero.

In Cuba, the Castro regime finally ended.

This week marked the 60th anniversary of the Bay of Pigs invasion, and it came with the confirmation that Cuba is now ruled by someone outside of the Castro family.

In 1961, the CIA supported a group of 1,500 Cuban exiles to launch an invasion of Cuba. The plan was to leverage the exiles to overturn Fidel Castro's government, which had come to power following a revolution. The group was supposed to land in the Bay of Pigs in southern Cuba, secure the area, and Cuba’s government-in-exile would then be flown in. CIA anticipated a mass uprising in support of the exiles.

Yet the plan failed miserably and the anticipated mass uprising never took place. Rather, the exiles were fired on by the locals and eventually captured by the Cuban military. This act of aggression and the failed US-backed invasion served to solidify Castro's position and gave him a legitimate reason to move closer to the Soviet Union.

The Castro family has had a firm grip on the power since then, despite decades of economic sanctions imposed by the United States. Fidel Castro survived numerous assassination attempts, and Raul Castro, the younger brother of Fidel, followed Fidel's lead and took over as Cuba's head of state after Fidel's death in 2016.

But change is finally coming on Friday of this week. In an event commemorating the Bay of Pigs invasion, Raul Castro announced that he was stepping down. His handpicked successor, Miguel Díaz-Canel Bermúdez will replace Castro at the top, who will retain a strong voice behind the scene.

Looking at Afghanistan and Cuba, it is clear that driving a change of regime is neither quick nor easy, even for a dominant power like the United States. In Cuba, the Castro regime did not collapse. In Afghanistan, the Taliban regime was removed but eventually bounced back, and the US-backed civilian government is corrupt and broken. Whether it is through military actions or financial sanctions, the opponents are likely to be way more resilient than you first expected.

Japan to release treated radioactive water into the Pacific Ocean.

In Japan, a major decision looms which may affect the world for more than the next few decades.

This week Japan announced that more than one million tons of treated radioactive water, or roughly equivalent to 500 Olympic-size pools, will be released into the Pacific Ocean in two years. Ever since the 2011 tsunami destroyed the Fukushima nuclear power station, water has been building up on the site. Some of the water was used to cool the damaged reactors, while rainwater landing on the plant, and groundwater was also collected.

The water collected has been treated for radioactivity, but a level of tritium remains. Tanks of water have been accumulated over the past decade, but now Japan's government claims that it will soon run out of space to store them They believe that releasing the treated water into the ocean is the best course of action, while activists are asking for the water to be stored until there is better treatment technology.

Some scientists, including those at the International Atomic Energy Agency (IAEA), have agreed with the Japanese claim that it is safe to release the water. But a release at this scale is unprecedented and it is unclear whether there may be unanticipated consequences. What if there is? Just like the Afghanistan war, perhaps there is no plan B.

Perhaps the bigger nuclear challenge in the Pacific Ocean lies not with Japan, but with the Marshall Islands, a tiny Pacific nation. The former U.S. colony was the site of more than 40 nuclear tests in the 1950s and 1960s, and over 100,000 cubic yards of radioactive debris resulted from the tests. Before the U.S. left and handed independence to the Marshallese, the military simply built a concrete dome covering the debris. Now with rising sea levels, there is a real possibility that the dome is leaking and may eventually collapse, bringing the debris into the ocean.

Thanks to a special report done by the LA Times, the world is finally beginning to pay attention to this. A recent report by the U.S. government claims that the dome is “not in immediate danger”. It remains to be seen if we will take any action before immediate danger arrives.

A decision today to act, or not to act, could change our next decades.

This article is part of the Making History This Week series.