Wreckage from the nose section of a Malaysian Airlines Boeing 777 plane which was downed on Thursday is seen near the village of Rozsypne, in the Donetsk region on July 18, 2014. Reuters/Maxim Zmeyev

U.S. President Barack Obama said in a press conference Friday that the United States government had concluded Malaysia Airlines flight 17 was shot down by a surface to air missile fired from an area controlled by pro-Russian separatists.

The president's comments came on the heels of an annoucement by Samantha Power, U.S. ambassador to the United Nations, that investigators “cannot rule out technical assistance from Russian personnel in operating the system” that downed the plane.

Russian President Vladimir Putin has denied that Russia was involved, and blamed Ukraine for the tragedy, but the United States and Ukraine have agreed that it was very likely a Russian-built Buk missile launcher.

This raises questions about how this advanced piece of equipment was able to bring down an airliner while being operated by pro-Russian separatists, who until this point have been identified as a sort of ragtag militia.

“It requires an extensive crew, a dozen men, and they all have to be highly trained,” said Steve Zaloga, a senior analyst at Teal Group in Fairfax, Virginia, and an expert in Russian military technology. “Some of the tasks are less complicated, like more administrative tasks, but difficult training is required either way.”

According to Zaloga, it’s not as if the pro-separatists just found the launcher and pointed it at the aircraft. First of all, operating the launcher typically requires two or three other other radar vehicles and a supporting command system.

“All of the vehicles have to interact together at the same time, which is why the U.S. government is suspicious about who was helping them use the equipment,” Zaloga said.

One possible theory on how the Buk ended up in the hands of the seperatists, according to Zaloga, who cited Russian and Ukrainian press reports, is that the pro-Russian separatists took over an entire missile defense battalion in Donetsk and forced or convinced the commander of the base to switch sides and help them use the systems. “If not that, then assistance must have come from Russia,” he said. "Russia certainly have plenty of crews they could send over and help train the seperatists, but it could be a mixture of the two."

Each Buk battalion contains up to 36 vehicles with one command vehicle, and is split into around 12 battery units which all have one target acquisition radar, which would have been used to target MH17; vehicles transporting and launching the actual missiles; radar vehicles, which are used to guide the missile to the target; and another support vehicle. The launch mechanism takes no more than five minutes to set up and only takes around 22 seconds to launch after the target has been identified.

"Before the missile is launched the crew feeds data into the initial guidance system and sends the missile to a certain point in the sky," said Zaloga. "It's a complex process, but an airliner is an easy target because it generally moves in a straight line."

After the missile is launched it would only take another minute before it impacted.

While Zaloga said that it was “extremely incompetent to shoot a weapon like that at an unidentified target” he did concede that the operating crew probably didn’t know what they were shooting at, because they would not have been connected to the civilian air traffic system that helps identify what is civilian and what is a military target.

One of the problems with older Buk systems is that because they were designed in the 1980s and used primarily to defend Soviet army equipment, they don’t have the ability to read the data sent by a civilian aircraft's transponder, which would identify the plane as a commercial jet.

“So when those guys are looking at a target they don’t have the same sort of information that the air traffic controllers have,” Zaloga said. “All they know is a target is travelling at 33,000ft. That’s it.”

When connecting with the target, the missile is designed to loop over the top of the target and use gravity to gather force and smash down upon its target. There's a chance the passengers on the aircraft might have seen the missile as it approached and passed over the top of MH17. Once the missile has been launched the radar guides it in automatically.

“On the screen there would be a target identified using a symbol and the Buk would do the rest,” Zaloga said. “This happens at such speeds that a human couldn’t control it. It’s all automatic after the launch starts.”