The banned Jamaat-ud-Dawah (JuD) head walked free on Friday after the Pakistan government decided against detaining him further in any other case. He was under house arrest since January this year.
"Ridiculous...," Gabbard, who is also the co-chair of the House Congressional caucus on India and Indian Americans said in a lengthy tweet.
"Not only did Pakistan give refuge to Bin Laden, responsible for attacks against US on 9/11, Pakistan set free a terrorist who has a USD 10 million American bounty on his head," she said.
In another tweet, she slammed Saudi Arabia for the spread of extremism across the world.
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"But no more absurd than President Trump's tripling down on US support for Saudi Arabia, which continues to spread extreme Wahhabi Salafist ideology around the world, fuelling terrorist groups like ISIS and al-Qaeda, all while paying lip service to 'defeating terrorism'," Gabbard said.
Richard Haas, head of the Council on Foreign Relations, a top American think-tank, called for tougher measure against Pakistan.
"Pakistan has harboured terrorists for years and provides sanctuary to the Taliban. It is a mystery why they are designated and treated as a Major Non-NATO Ally when the reality is Pakistan is anything but," Haas said.