The dirty little secret of the intelligence world is that much of what you really need to know isn't exactly a secret anyway.

Sheikh Rahman had a doctorate in Islamic jurisprudence from al-Azhar University in Cairo, the Harvard of Islamic thought. He also had a long history of guiding terrorist groups.

Trump, of course, has been very wrong in the past about important issues such as President Barack Obama's place of birth and Mexican immigrants, but the Republican frontrunner is correct in saying that former Republican President George W. Bush did not keep the country safe during the 9/11 terrorist attacks.

The rise of ISIS starts with a Jordanian thug named Abu Musab al-Zarqawi who founded ISIS' parent organization, al Qaeda, in Iraq. What gave Zarqawi the opportunity to create al Qaeda in Iraq? It was, of course, George W. Bush's decision to invade Iraq in 2003.

The Bush administration's approach to the war on terror collided badly with another of its doctrines, spreading democracy in the Middle East as a panacea to reduce radicalism.

The Turkish government will never tolerate the creation of a Kurdish state.

Between November 23, 2002, and January 11, 2003, al-Qahtani was interrogated for 48 days at Guantanamo more or less continuously, kept awake for much of that time by loud music being blasted when he was falling asleep, doused with water and subjected to cold temperatures, kept naked and forced to perform tricks as if he were a dog.

An intelligence officer and historian, Rayburn published a 2014 book, 'Iraq After America,' which is a must-read for anyone who wants to understand how Iraq descended into chaos in the years after the American troop withdrawal at the end of 2011.

The documentary feature film 'Legion of Brothers' tells the stories of the handful of U.S. Special Forces soldiers who, shortly after the 9/11 attacks, went into Taliban-controlled Afghanistan and, within a matter of weeks, overthrew the Taliban regime.

Rather than making loose and unsubstantiated claims that Obama and Clinton created ISIS, it would behoove Trump if he advanced some real policy ideas about how to solve the Syrian and Iraqi civil wars. Of course, to do that he would have to get beyond the inflammatory slogans and sound bites that have characterized his campaign.

America has not traditionally been the cramped, frightened country of Trump's executive order that bans Syrian refugees.

As early as 1993, members of bin Laden's group had been planning an attack on the American Embassy in Nairobi, Kenya.

What did U.S. officials have to lose by saying that bin Laden was being protected by the Pakistanis, if it were true?

A decade and a half ago, the U.S. Air Force dropped massive 15,000-pound 'Daisy Cutter' bombs on the Tora Bora complex where Osama bin Laden was hiding in December 2001.

The money that bin Laden inherited was about 20 million dollars over the course of many years, not the much larger sums some have suggested. In 1994, his family cut him off.

Often it is important to listen to what people aren't saying.

Both China and Russia felt duped by the U.N. 'no-fly' zone resolution regarding Libya in 2011 that eventually led to the ouster of Libyan dictator Moammar Gadhafi. China and Russia had abstained from the Libyan resolution, and neither country plans to make what they regard as a similar mistake again.

When Abu Zubaydah was shown a series of photos of al Qaeda members by Soufan, he identified one of them as the operational commander of 9/11, Khalid Sheikh Mohammed.

The reason that Islamist militants can assert that jihad is necessary against the perceived enemies of Islam is that there is sufficient ammunition in the Quran to buttress their beliefs. The same could also, of course, be said for the Old Testament, which is full of scenes of violent death visited on the enemies of God.

In the past, Joint Special Operations Command, or JSOC, of which SEAL Team 6 is a key component, has only launched ground raids in Yemen when the lives of hostages held by al Qaeda seemed at risk.

ISIS' key social media-encrypted platform is Telegram, which is engineered by a Berlin-based tech company that can simply ignore the rulings of American federal judges as well as legislation passed by the U.S. Congress.

It is in American and Afghan interests for the U.S. to stay in Afghanistan so it doesn't turn into Iraq circa 2014, with the Taliban controlling much of the country while hosting a strong presence of ISIS and al-Qaeda as well as every other jihadist group of note.

A key flaw of the Obama administration's approach to Afghanistan has been constantly announcing proposed withdrawal dates for U.S. forces, which has enabled the Taliban to believe they can simply wait out the clock.

For many terrorists, carrying out an attack allowed them to become the heroes of their own story.

Afghanistan's winters in the north are legendarily harsh, and southern Afghanistan, by contrast, is bleak desert. These difficulties are compounded by the fact that Afghanistan is one of the world's most heavily mined countries.

If the party of Lincoln wishes to become the party of intolerance, selecting Trump to be its presidential candidate is a good way forward.

Trump himself has not laid out a clear agenda on the national security issues that are the most pressing for the United States, from the resurgence of the Taliban in Afghanistan to the deepening Syrian civil war to the fight against ISIS in Iraq and Syria and the flexing of Russian muscles under President Vladimir Putin.

Candidate Trump had previously opined that 'Islam hates us' and had called for 'the total and complete shutdown of Muslims entering the United States,' an argument he has since modified and moderated.

The only lethal terrorist to immigrate to the United States as an adult and conduct an attack shortly after arriving is Tashfeen Malik, who was born in Pakistan.

Donald Trump's own mother Mary escaped the bone-crushing poverty of Scotland's remote Outer Hebrides for the promise of New York in 1929.

Officials in the George W. Bush administration later criticized the cruise missile strikes that were ordered by President Bill Clinton in Afghanistan in 1998 as only 'pounding sand.'

On November 28, 2016, Abdul Razak Ali Artan, an 18-year-old legal resident of the United States whose family was originally from Somalia, used a car to mow down a group of people at the Ohio State University.

In quiet ways far too complex to hold Trump's interest, Muslims in the United States and around the world are helping every day to prevent massacres such as Orlando from happening.

More than a decade and half after 9/11, U.S. military actions in countries such as Syria, Iraq and Afghanistan and several other Muslim nations are governed by the Authorization for the Use of Military Force (AUMF) that was passed in the days immediately after 9/11.

Ground operations are inherently very risky in Yemen. The two previous JSOC raids in Yemen were both in 2014.

Because of the 9/11 attacks, the framing of terrorism by politicians, the media, and the public too often in the past decade and a half has been that it is Islamist political violence that is the terrorism we need to be concerned about.

The dangers of TATP bombs can be seen in the case of Matthew Rugo and Curtis Jetton, 21-year-old roommates in Texas City, Texas. They didn't have any bomb-making training and were manufacturing explosives in 2006 from concentrated bleach when their concoction blew up, killing Rugo and injuring Jetton.

Hydrogen peroxide-based bombs were used in the London bombings in 2005; in al Qaeda's foiled plot to attack subways in New York City in 2009 and also in the ISIS-directed Paris attacks in 2015 and the ISIS-directed attacks in Brussels a year later.

Common sense would tell you that the idea that Saudi Arabia was paying for bin Laden's expenses while he was living in Abbottabad is simply risible. Bin Laden's principal goal was the overthrow of the Saudi royal family as a result of which his Saudi citizenship was revoked as far back as 1994.

The reason that attacks by American terrorists who are not jihadist militants are sometimes not called 'terrorism' is, in part, because in the United States, terrorism is a crime which has to be in some way be associated with a 'designated' terrorist group such as ISIS.

For many, embracing the ideology of Osama bin Laden or ISIS allowed them to become the heroes of their own story as well as actors in a cosmic crusade. For others, a 'cognitive opening' to militant Islam was often precipitated by a personal disappointment or loss.

Think of ISIS as a pathogen that preys on weak hosts in the Muslim world. In fact, there is something of a political law: The weaker a Muslim state, the stronger will be the presence of ISIS or like-minded groups.

Virulent anti-Semitism is, of course, a staple of militant Islamist ideology.

American jihadists are generally motivated by a mix of factors, including dislike of U.S. foreign policy in the Muslim world.

Mohammed Taheri-Azar, a naturalized U.S. citizen hailing from Iran, crashed his SUV into a crowd at the University of North Carolina at Chapel Hill in 2006, injuring nine people.

What bin Laden had hoped to achieve in Afghanistan in the post-9/11 period, which was to drag the United States into a protracted guerrilla war like the one he had fought against the Soviets, never happened. Instead, that protracted guerrilla war is now playing out in Iraq, in the heart of the Middle East.

I stepped into the bedroom where he was killed and looked up at the ceiling, where you could still see the patterns of blood that had spurted from bin Laden's head when the bullet fired by a U.S. Navy SEAL tore through the terrorist leader's face.

Tamerlan Tsarnaev, one of the two brothers who carried out the marathon bombing, was a non-practicing Muslim who only became an Islamist militant once his dreams of becoming an Olympic boxer faded. At the time of the attack, he was unemployed.

Because Scotland and Northern Ireland want to remain part of the E.U., there is the quite real possibility that Scotland and even Northern Ireland might now choose to go their own way on membership within the E.U. and the 'United Kingdom' would suddenly effectively be only England and Wales.