At www.space.com/32028-large-ish-meteor-hits-earth-but-no-one-notices.html … the largest meteor to enter the atmosphere during the last 2 years, since Chelyabinsk, occurred over the South Atlantic Ocean on February 6th.
At http://phys.org/print375696755.html … the South Atlantic meteor is again mentioned – estimated at 5m across. It exploded with the force of 12,000 tons of TNT (but there was nobody around to see it). This can be compared to Chelyabinsk meteor of 2013 which exploded with the force of 500,000 tons of TNT (big difference). There was another one in 2008, exploding above the Sudan with the force of 1000 tons of TNT. This was the first one to be tracked prior to arriving at the Earth. What may have been happening earlier to the setting up of defence and security systems is anyone's guess. We do know about the 1908 Tunguska meteor – which exploded with the paower of 1.5 million tons of TNT.