Mike Flynn reuters President-elect Donald Trump's newly appointed national security adviser, retired Lt. Gen. Mike Flynn, has outlined his plan to defeat terrorism extensively in recent months.

One of Trump's earliest national-security aligned supporters, Flynn wrote a book, did a circuit of media interviews, and spoke on behalf of Trump's campaign during the general election.

His book, "The Field of Fight: How We Can Win the Global War Against Radical Islam and Its Allies," which focused on the importance of identifying "radical Islam" and its role in terrorism. He defined the fight against terrorism as a "world war" and emphasized the need to begin the fight at home.

"If we cannot criticize the radical Muslims in our own country, we cannot fight them either in America or overseas," Flynn wrote in the book's conclusion. "Unless we can wage an effective ideological campaign in the United States, we will not be able to defeat the jihadis on foreign battlefields, because we will not understand the true nature of our enemy."

Such views have led to Trump's decision to appoint Flynn national security adviser being met with criticism.

Flynn was formerly the head of the Defense Intelligence Agency, and he spent years fighting terrorist groups in Iraq and Afghanistan. Flynn was fired from the DIA in 2014, and he claims it's because he took a stand about "radical Islam." Other accounts, including those of former officials relayed to The Washington Post, have blamed his management style.

Flynn has also emphasized the need for looser rules of engagement for US soldiers in the Middle East and for a new intelligence-driven strategy. He wrote about "attacking the enemy alliance" — Russia and Iran — and strengthening the US' own alliances.

Flynn sat down with Business Insider after his book came out and provided more insight into his strategy.

"This is where Muslims leaders in the Muslim world have to stand up and be counted," Flynn said. "And right now they're not. And I think we have to be, we have to use tough diplomacy — tough love, if you will — to get them to be counted about where do they stand on this particular aspect of their political system."

He has come under fire before for referring to Islam as a "political ideology" rather than a religion.

Flynn has also framed the fight against the terrorist group ISIS as a war against an ideology rather than simply a war against militants on battlefields in Iraq and Syria.

"We're losing this ideological war," Flynn said. "They were beating the most sophisticated military coalition brought to bear since WWII in 2006 in Iraq, in 2009 in Afghanistan."

And he has expressed a desire to commit to overseas engagements. He criticized the Obama administration's troop drawdown in Iraq, which some experts say created a power vacuum that allowed ISIS to rise up.

"We beat [Al Qaeda in Iraq] in 2011," Flynn said. "We proved that their version of, their Allah, couldn't help them on the battlefield. But though a political decision by President Obama, he decided to pull everybody out. When you have victory in warfare, you must sustain that victory. And we did not."

Flynn has also said he agrees with Trump that the US military should be more careful about not showing its hand to the enemy.

"What we are talking about here is options," Flynn said. "Giving our country options against any enemy that we face, whether it's China and cyber or Russia and nuclear weapons or ISIS and radical Islamism, whatever that is, we want to give our country options, and what we want to do is we want people to ... wonder what options we still have. What we cannot do is we cannot give away, we cannot show those cards."