Did Ukraine Air Force Cause MH17 Crash?

Did a Ukrainian Air Force Su-25  in effect guide a missile from a Buk missile launcher to  Malaysian flight MH17?   Did Russian separatists fire at an Su-25 which had dropped down toward the ground after flying as an "escort"  and then began climbing back up toward MH17 with the missile on its tail? 

[Note:  I've delayed posting this because of recent reports attributed to unnamed American intelligence sources supporting a theory that a Ukrainian air force plane shot down MH17 after it deviated from the normal course.   Ukrainian authorities could have interpreted the different course as an indication of a plane controlled by terrorists.  We will need to watch this theory to see if it replaces the theory that a Buk missile brought down MH17.   For now the Buk theory seems to provide the best explanation.]

Russian authorities report that there was an Su-25 approaching MH17 prior to the disaster.  “A Ukraine Air Force military jet was detected gaining height, it’s distance from the Malaysian Boeing was 3 to 5km [about 3 miles],” the head of the Main Operations Directorate of the HQ of Russia’s military forces, Lieutenant-General Andrey Kartopolov told a press conference.   Air Force Lieutenant-General Igor Makushev said the Ukrainian  jet was "scrambling in the direction of the Malaysian Boeing."

The Russian descriptions of the Su-25's flight is consistent with a plane coming up to the MH17 as would have been the case if it had dropped down to investigate or attack a ground target.   If the Su-25 had merely been escorting MH17 it would have been flying at a constant height and been matching the speed of the  airliner.  It can climb at the rate of 2 miles per minute which means it could travel from near ground level to an elevation of 3-5 km below the MH17  in a couple of  minutes.  

Gen. Makushev's use of the word "scramble" is significant because the term is used to describe the behavior of a pilot getting in position to deal with a threat.    A pilot attempting to get away from a missile would fly in a similar hurried way.  

WashingtonsBlog reports that "a Youtube video made a month before Malaysia Airlines Flight 17 was shot down alleges that Ukranian fighter jets were hiding behind passenger planes, pulling away temporarily, dropping bombs on Ukrainian separatists, and then hiding again behind the plane. "

The Aviationist reports that Su-27 Flanker jets had been escorting civilian jets over Ukraine.    

If Russian separatists were operating  a Buk missile system that shot down MH17, they likely  would have been inexperienced.   They might not have understood the transponder codes in the radar readout or been too preoccupied with shooting down the Su-25 to notice MH17.  Inexperienced operators would likely have relied on visual identification of potential targets and merely used the radar to guide the missile to its target.  Smart guerrilla fighters know to keep the radar turned off unless they know they have a possible target because the enemy could detect the electronic signature of the radar. They might have visually identified the Su-25 and quickly fired without bothering to check to see if other aircraft were in the area.  Aviation Week reports that the Buk system can have a problem distinguishing among different potential targets if it doesn't have the appropriate support equipment.

If the Su-25 was headed toward MH17, the MH17 might have been mistakenly been targeted or a slight change in course by the Su-25 could have resulted in MH17 becoming the target.   I'm not familiar with the handling characteristics of the Buk missile, but a missile traveling at 2,000 mph [0.5 miles per second] requires a significant distance to change directions.

Separatists could have thought the presence of the Su-25's meant the larger plane was a high value target.   

I recognize the possibility that Ukrainian troops might have shot down MH17 so they could blame the action on Russian separatists,   but it seems unlikely Ukrainian troops would deliberately have taken a chance on firing at MH17 with their own jets so close.  The site "abovetopsecret"  claims that   the U.S  has satellite imagery indicating Ukrainian troops, who may have been fooling around while  drinking, might have launched the missile either by accident or as a badly timed prank. Blacklisted.com also supports this scenario. We see this scenario occasionally in military themed comedy movies or television episodes but don't expect such things to happen in real life. This plausible scenario could explain why American authorities started calling the incident an "accident".    In the movies such accidents result in victims in tattered clothes and apparent soot on exposed skin.  Victims of real . life "accidents" are seldom so fortunate.

Ukrainian and American authorities have accused the Russian government of providing the Buk launcher to the separatists, but it isn't unusual for rebel forces to steal weapons and munitions from the government.   Individuals in government sympathetic to the rebels sometimes aid this process. Ukrainian separatists likely have agents in the Ukrainian military like the Viet Cong did in the South Vietnamese army.  Commanders who have had large items stolen might be reluctant to tell their superiors about their losses. They may lie and say the stolen items were destroyed.  In Vietnam, the Viet Cong sometimes used stolen weapons against us.  

If Russian weapons are being provided, individual commanders,rather than senior military officials   might be responsible.  Individual commanders  might occasionally  "loan" weapons to separatists who might be friends or relatives,    Military units sometimes rely on "unofficial actions" in such situations.   In the movies a crusty old 1st sergeant will take some action he knows his commanding officer wants done, but has been ordered not to do.  

Both Russia and the United States have assisted rebel groups in many countries in recent decades.   The Russian government is under pressure from friends and relatives of ethnic Russians in Ukraine to assist the separatists.  In the 19th Century the United States went to war with Mexico to support "separatists" in  Texas and California who wanted independence from Mexico.