Conversation so far:
What did Gulbuddin Hekmatyar do after 9/11?
Gulbuddin Hekmatyar declared his opposition to the US campaign in Afghanistan and criticized Pakistan for assisting the United States.
Was Gulbuddin Hekmatyar connected to Osama bin Laden?
In January 2007 CNN reported that Gulbuddin Hekmatyar claimed that his fighters helped Osama bin Laden escape from the mountains of Tora Bora five years ago.“
Why did Gulbuddin Hekmatyar claim that he helped Osama bin Laden?
In May 2006, Gulbuddin Hekmatyar said he was ready to fight alongside Osama bin Laden and blamed the ongoing conflicts in Palestine, Iraq and Afghanistan on U.S. interference.
What did the United States say about Gulbuddin Hekmatyar?
On February 19, 2003 the United States State Department and the United States Treasury Department jointly designated Gulbuddin Hekmatyar a global terrorist.

Question: Why did the U.S. call him a global terrorist?
Self-contained rewrite: Why did the U.S. call Gulbuddin Hekmatyar a global terrorist?