Samuel "Sandy" Berger, a former national security advisor under the Clinton administration, died on Wednesday at the age of 70 from cancer.

Berger's longtime aide and friend Tara Sonenshine announced his death, which came more than year after he was diagnosed with cancer, reports The New York Times.

"Some thirty years ago, when I first arrived in Washington and didn't know very many people, Sandy befriended me and we remained close ever since," said Secretary of State John Kerry. "It helped that we shared a deep love of foreign policy. He was a serious man, but also easygoing, with a dry wit, a ready laugh, a bone-crushing handshake, and the ability to offer thoughtful guidance on almost any subject under the Sun. Over the years, we compared notes often about such topics as international trade policy, nuclear nonproliferation, the fight against terrorism, and the pursuit of Middle East Peace. I will miss his friendship and counsel."

Following his death, Bill Clinton released a statement expressing his condolences for Berger, who he described as a political confidant and a friend.

"He was a trusted advisor to my campaign for President and an essential member of our national security team afterward," wrote Clinton in a statement published on the Clinton Foundation. "Nobody was more knowledgeable about policy or smarter about how to formulate it. He was great both in analyzing a situation and figuring out what to do about it. His gifts proved invaluable time and time again, in Latin America, the Balkans, Northern Ireland and the Middle East."

President Barack Obama also released a statement, calling Berger "one of our nation's foremost national security leaders." He added that "his legacy can be seen in a peaceful Balkans, our strong alliance with Japan, our deeper relationships with India and China," according to Politico.

Just a day before he died, Berger warned his colleagues at his consulting firm, the Albright Stonebridge Group, about his deteriorating health with the ominous message "time is not on my side."

Secretary of State Madeleine Albright also released a statement through The Albright Stonebridge Group, which she and Berger founded and operated together.

"Our country is stronger because of Sandy's deep and abiding commitment to public service, and there are countless people whose lives he changed for the better. I am certainly one of them. He was one of my dearest friends and among the wisest people I have ever met," she wrote. "I will always treasure our decades-long partnership, both in and out of government, and I will be forever proud of what we accomplished together."

After working under the Clinton administration, Berger was fined and sentenced to community service after pleading guilty to removing classified documents from the National Archives, reports CNN.