My opinions only, no facts here:
Terrorism is well down my list of possible causes, as is a missile-strike. But for the sake of completeness, let us examine the terrorism and missile-strike angles. If this was a terrorist act, there MUST have been a target. I simply do not buy the flying into the middle of nowhere theories. One target that has not been discussed would be a ship at sea conducting naval exercises. This leads naturally to the missile-strike theories: 1) a missile fired during military exercises brought the plane down by accident, or 2) the plane was approaching a ship on a suicide attack and was shot down as a defensive action.
To make a long story short, here is what I have learned about military exercises in the region where the plane disappeared. I did a careful search on the internet. Where practical, I configured Google Advanced Search to screen out hits where the disappearance of MH 370 was already known to the sites writers. Before reading below, remember that March 8, 2014 is the day in Malaysian-time when the plane disappeared, but I cannot be sure in some instances on which side of the International Date Line that individual reports are based from.
The AUSTHAI military exercise in the Gulf of Thailand is biennial, last held in 2013. So, there should be no exercise until 2015. This exercise could not be involved.
The MILAN 2014 biennial military exercise in the Andaman Sea was conducted from Feb. 4th to Feb. 10th. This involved 17 nations. The activity timeline is solid, so this exercise clearly pre-dates the disappearance of MH 370.
The Cobra Gold exercise is an annual event involving Thailand, Singapore, Japan, Indonesia, South Korea, Malaysia, and the U.S. The official? dates for this exercise in 2014 are Jan. 1 through Feb. 22. Oddly, one official site claimed the opening ceremony was on Feb. 11, and another site stated that the exercises are on Feb. 11 to 21. Regardless of such trivial discrepancies, this military exercise pre-dates the disappearance of MH-370.
Exercise Key Resolve is located in or near South Korea and ended on March 3 or March 6. Besides Korea, the U.S., Australia, Canada, Denmark, and the United Kingdom participated. This activity also involves exercise Foal Eagle, from March 3 to April 18. A third and related exercise, Ssang Yong, was held from March 27 to April 7. Although there is some overlap in time with the disappearance of MH 370, these three exercises are probably far-removed from the region where the plane disappeared.
The Western Pacific Naval Symposium Mine Counter Measures and Diving Exercise took place in the New Zealand region from Feb. 17 to March 7. This involved 14 nations, including New Zealand, Australia, South Korea, Malaysia, Thailand, and the U.S. Since this exercise ended by March 7 and is so far away, it should not be related to the disappearance of MH 370.
Exercise Cope Tiger involves air power and is conducted between Singapore, Thailand, and the U.S. This year's exercise involved 76 aircraft, 42 ground-based air defense systems, and about 2,000 personnel from the participating nations. Although by itself, this info could raise a few eyebrows, the flying-training portion of this exercise was conducted from March 10 to March 21. I confirmed this time-span independently. So this exercise post-dates the disappearance of MH 370.
OK, I admit that I saved the best for last! There is the military exercise called CARAT. CARAT consists of a series of bilateral exercises held annually in SE Asia. The countries involved are Bangladesh, Brunei, Cambodia, Indonesia, Malaysia, Philippines, Singapore, Thailand, and the U.S. Navy. According to
http://www.public.navy.mil/surfor/Pages/carat-2014.aspx#.U3_E0HY_X6g, this exercise runs from May 24 through November 10. BUT, I also looked at the Google Cache (earlier version) for this same page and that earlier version of the page shows the military exercise runs from Feb. 24 through November 10! As you will see, this exercise probably did begin in February, rather than May. According to
http://www.uscarriers.net/ddg100history.htm, the USS Kidd anchored off Dili, Timor-Leste on Feb. 21 for a six day port visit to participate in the CARAT exercise. The opening ceremony for the Timor-Leste CARAT exercise is reported for Feb. 24. It gets somewhat confusing here, since Feb.26 is reported as the end of the 2nd CARAT Timor-Leste exercise. Only one or two days for the military exercise? What I think is going on is this: CARAT is a large and complex regional military exercise carried out over a long period of time in which the USS Kidd participated for at least a brief amount of time in Timor-Leste. Presumably, there are numerous CARAT activities beginning and ending throughout the region at any time from Feb. 24 through Nov. 10. As a possible example, the USS Bonhomme Richard conducted refueling (no small affair-600,000 gallons of diesel) in the East China Sea on March 7. The USS Bonhomme Richard was said to be conducting joint-force operations in the 7th Fleet Area of Responsibility. Regarding two particular guided-missile ships from the U.S. (Destroyers), the USS Kidd and the USS Pinckney: I do not know what the USS Kidd was doing after Feb. 26 until it appeared in the Gulf of Thailand on March 10 to search for MH 370. I also possess no knowledge of the activities of the USS Pinckney after Feb. 17 (when it anchored in Hong Kong) and before March 9 (when it arrived off the southern coast of Vietnam to assist in the search for MH 370). BUT, the almost simultaneous appearances of the USS Kidd and USS Pinckney in the Gulf of Thailand to assist in the search for MH 370 could mean they were both already in the near-region to participate in the CARAT military exercises.
All info provided above should be considered as my opinions only.
Sleuth On!