Act of Valor

In the Philippines, a terrorist kills the U.S. ambassador, his son, and dozens of children at an elementary school, using a vehicle-borne IED disguised as an ice cream truck. The mastermind, a Chechen terrorist named Abu Shabal (Jason Cottle), escapes to a training camp in Indonesia. Elsewhere in Costa Rica, two CIA operatives, Walter Ross (Nestor Serrano) and Lisa Morales (Roselyn SÃ¡nchez) meet to consolidate intelligence about their target, a drug smuggler named Mikhail "Christo" Troykovich. Christo's men kill Ross and capture Morales, who is imprisoned in a jungle compound and tortured.
At Coronado, the members of Bandito Platoon, SEAL Team Seven are at home. Lieutenant Rorke (Rorke Denver) confides to Chief Dave that his wife is pregnant and has the entire team spend time together with their families until their next deployment. A squad from the platoon consisting of Rorke, Dave, Wiemy, Mikey, Ray, Sonny, and Ajay, is then deployed to Costa Rica to exfiltrate Morales.
The seven Navy SEALs insert into the jungle via HALO and hold position outside the compound all night. At dawn, they approach the compound, hear Morales being tortured, and decide to enter the compound early. Rorke and Weimy, the team sniper, provide cover for the other five, led by Dave, who conduct room-clearing, engaging several enemy guards. SEAL operative Mikey is shot in the eye, blinding him and knocking him unconscious, though he survives. The SEALs extract Morales, escaping with her and recovering a cellphone full of the information she had gathered. However, the gunfight alerts the enemy quick reaction force down the road, who drive toward the camp. The SEALs commandeer an enemy truck and exfiltrate. The hot pursuit forces them to revert to a tertiary extraction point where the SOC-R boats extract the team and neutralize the enemy pursuit with miniguns.
Christo and Shabal, who are revealed to have been childhood friends, meet in Kiev. Christo knows the CIA is watching him and informs Shabal that subordinates will complete their project. Shabal is enraged, but he goes to a factory, which is assembling extremely powerful bomb vests that can evade metal detectors and are thin enough to be worn under any clothing without attracting attention.
On the amphibious assault ship USS Bonhomme Richard, Rorke is informed that the intelligence recovered confirms Shabal and Christo were working together. Shabal, an old-school Muslim terrorist, seeks to bring jihad to the U.S., while Christo is not merely a drug dealer, but a smuggler, with routes and contacts for smuggling people into the U.S. Two of the SEALs, Ajay and Ray, are sent to Somalia, where an arms transfer involving Shabal is taking place. The remaining SEALs, comprising Rorke, Dave, Sonny and Weimy, stay in the U.S. in case the terrorists make it in. Miller himself has been reassigned to SEAL Team Four, hunting for Christo somewhere on the oceans. Lieutenant Rorke gives Dave a letter to give to his family in case he is killed.
The two SEALs parachute from a C-130 transport plane off the coast of Somalia to rendezvous with a submarine. There, they confirm the presence of Shabal and sixteen terrorists. They track their plane to an island off Baja California, where the team stages an assault. They successfully attack and secure the island, killing eight terrorists, although Shabal and the remaining eight escape. Elsewhere, in the South Pacific, SEAL Team Four successfully captures Christo. Interrogated and threatened with permanent separation from his family along with other implied sanctions, Christo reveals his connection with Shabal and his plans to have his martyrs detonate their vests at strategic points throughout the U.S., causing a panic and doing economic damage surpassing that following the September 11 attacks.
The SEALs are informed that Shabal is en route to the U.S. via tunnels underneath a milk factory, and are ordered to link up with Mexican Special Forces and neutralize the remaining targets. Arriving at the factory, the SEALs and Mexican forces launch an assault there. During the gunfight, a combatant throws a grenade, and Rorke dives on it to save his team before it detonates, killing him. Dave pursues the terrorists and shoots them as they try to escape through the tunnels. He is then shot several times and gravely wounded by Shabal, who is intercepted and killed by Sonny before he could execute Dave.
At home, Rorke is given a military funeral with full honors, where the SEALs pay their respects. It is then revealed that Dave's narration throughout the movie was a written letter meant for Rorke's son. The film ends with a dedication to every U.S. Navy SEAL killed in action since 9/11 along with a listing of their names as well as a photo montage of other everyday public servants (soldiers, police, firefighters, etc.).

Question: Who revealed to have been childhood friends?
Answer: Christo and Shabal; Christo and Shabal