(CNN) John Bolton, Donald Trump's pick to be the next national security adviser, has a decade-long history of associating with anti-Islam activist Pamela Geller.

The former UN ambassador wrote the foreword to Geller's 2010 book that she coauthored with fellow anti-Islam activist Robert Spencer titled "The Post-American Presidency: The Obama Administration's War on America." Bolton also appeared twice on Geller's internet radio program "Atlas on the Air" and twice on her video blog.

Geller is well-known for her inflammatory public comments about Muslims and Islam and has long peddled the conspiracy theory that Muslims are attempting to impose Sharia law in the US. She once ran an ad campaign in New York City with taglines like, "It's not Islamophobia, it's Islamorealism" and "End all aid to Islamic countries."

Geller emerged in 2010 as a leading opponent of the mosque and community center that was then planned for a site near Ground Zero in lower Manhattan. She also organized a "Draw the Prophet" contest in Garland, Texas, in May 2015. The contest, which occurred in the aftermath of the Charlie Hebdo shooting in Paris that year and which Geller argued was an event in defense of free speech, was disrupted by two gunmen who attacked it and were ultimately shot dead.

Geller has long been a booster of Bolton, dating back to at least 2005 when she strongly supported him as President George W. Bush's pick to be the US ambassador to the United Nations.

Geller declined to answer CNN's questions about her relationship with Bolton and instead asked for corrections on past CNN coverage of her. The White House did not respond to a request for comment. A spokesperson for Bolton did not respond to a request for comment.

Bolton would make his first brief appearance on Geller's video blog in June 2006 while serving in the UN post, where he told Geller he was trying to keep UN bureaucrats from making decisions for the American people.

Bolton appeared on Geller's "Atlas on the Air" Internet radio show in November 2007, speaking for nearly an hour to promote his book at time, though the interview evolved into a wide-ranging discussion on Bolton's worldview.

Bolton agreed with Geller that the United Nations was an anti-Semitic institution. Geller also pressed Bolton on his thoughts on the alleged threat of "creeping Sharia," a conspiracy that she and other anti-Muslim activists hold that Muslims in America are stealthily trying to implement religious law in the United States courts.

Bolton answered, "I don't see it as much as a threat in the United States as it is Europe. Because I think in the United States, uh, we have made the melting pot into something that's unique in the world. And the melting pot means you can come from anywhere. You can come from any background, any ethnic group, any geo geographical region, any religion, any culture. And you can become an American. You don't have to lose your heritage, but you have to go through a process of assimilation."

Bolton then said it was a problem in Europe, and that European courts were in a crisis because they don't know how to handle Muslims who argue "Sharia should apply to Muslims and some other law should apply to everybody else."

After Geller pushed the subject further, Bolton said it was a problem in parts of the United States as well. "I think there are problems that we've seen in parts of the United States. I don't mean to say it doesn't exist, but I think we face a qualitatively different situation than the Europeans."

Bolton said the question of Sharia law and rising Muslim demographics would be one that they would be faced with in the future.

"I think the Europeans are more at risk than we are. But uh, but I, I acknowledge this is a, this is a question we're going to have to face in the coming decades as well."

In June 2008 , Bolton again appeared on Geller's internet radio show, mostly to discuss past election and the upcoming election and Bush administration actions.

"I didn't see the statements but, as the saying goes from the Franklin Roosevelt era, somebody said, 'not all Democrats are horse thieves, but all horse thieves are Democrats.' Taking that forward, the terrorists today are Islamic fundamentalists, that's where the threat lies, worldwide, and the worst threat of all, is obviously getting nuclear, chemical or biological weapons," Bolton said. "I think Romney in 2008 did suffer by comparison on national security issues, I think that's why many Republicans supported John McCain or either Fred Thompson, so part of Romney's burden going forward, if in fact he runs again, is to demonstrate that he can handle not only the domestic economic issues, but foreign policy questions as well."

In his 2010 foreword to Geller's book, Bolton wrote, "This book carries forward the ongoing and increasingly widespread critique of Barack Obama as our first post-American president."

In the book, Geller and Spencer argued that America and Europe face "creeping Sharia" and that "Europe is committing slow cultural and demographic suicide." The authors paint a picture of Obama as unwilling to confront the country's problems because he was "influenced and indoctrinated by many who despised America."

Geller and Spencer's critique of Obama is closely intertwined with their fear of Sharia law infiltrating the United States.

"His statements about meeting the challenge of the global jihad, however, were a de facto form of submission, an implementation of a soft Sharia: the quiet and piecemeal implementation of Islamic laws that subjugate non-Muslims," they wrote.