The War in Afghanistan
There have been many wars in Afghanistan throughout history. In the "Great Game", Britain invaded Afghanistan and tried to conquer it, though they failed. Russia also had an interest in the region, primarily because it wished to break through to the Indian Ocean and obtain a warm water port there. This put it into conflict with Great Britain, which held India (including Pakistan), and had interests in Iran.
In 1979, the Soviet Union invaded. They pulled out in 1989, largely due to an inability to defeat the Mujahideen, who were backed by the United States. During the Cold War, the United States waged a proxy war against the Soviet Union. The U.S. supplied the Afghans with arms including Stinger missles, soldier-launched weapons that were able to bring down Soviet helicopters.
The United States, supported by several other countries, invaded in 2001 because the Taliban government refused to hand over Osama bin Laden, leader of Al-Qaeda and planner of the attacks on September 11, 2001. This conflict is continuing and includes cross border skirmishes (often by predator drone missile strike) with forces based in Pakistan.
One resistance strategy the Afghans employed was forbidding the entry of railroads into their country. They continued this until 2012. Unfortunately this contributed to poverty, isolation, and backwardness.