Service members in army combat uniforms cheered as President Barack Obama praised troops at Fort Campbell, Ky., for their efforts in the war against terrorism.

Last week, special military units killed al-Qaida leader Osama bin Laden at a compound in Abbottabad, Pakistan.

Though Obama spoke publicly to the lively crowd, he earlier met privately with members of the special operations team that executed the invasion.

Among them were operators from the Naval Special Warfare Development Group, often called "SEAL Team Six," and pilots from the 160th Special Operations Aviation Regiment, nicknamed "Night Stalkers." These units, along with the Army's Delta Force, work for Joint Special Operations Command, or JSOC.

JSOC operatives are responsible for killing former Iraqi leader Saddam Hussein's sons and capturing Hussein himself. JSOC also tracked down al-Qaida's leader in Iraq, Abu Musab al Zarqawi.

The first four minutes of this video describes President Obama's visit to Fort Campbell, while the rest is an interview with former SEAL Team Six member retired Navy Commander Ryan Zinke and former Army Special Forces officer retired Col. Kalev Sepp.

PRESIDENT BARACK OBAMA: Thanks to the incredible skill and courage of countless individuals -- intelligence, military -- over many years, the terrorist leader who struck our nation on 9/11 will never threaten America again.

PRESIDENT BARACK OBAMA: It was a chance for me to say, on behalf of all Americans and people around the world, job well done.

MARC AMBINDER: Since 9/11, the units have turned into an army, a secret army within an army. They have incorporated intelligence elements, logistical elements, technological and development elements. And they really became the tip of the spear in the war against al-Qaida and the Taliban.

1. Who is Osama Bin Laden?

2. What is al-Qaida?

3. Name as many units of the U.S. military as you can.

1. Why did President Barack Obama travel to Fort Campbell, Kentucky?

2. Do you think the American public has the right to know who killed Osama bin Laden and obtain more information about the attack?

3. Is it a good idea to have a “secret army within an army?” Why or why not?