No, I do not. NASA co-ordinates the Near-Earth Objects project, scanning for various chunks of material that could cause a serious impact upon Earth. Current total of Near-Earth Objects ( the vast majority of which are categorised as benign because of size of object and/or distance and trajectory in relation to Earth) is, I think, around 50,000 or so now, but the list of potentially hazardous objects is a great deal smaller. ( 200 or so ).
This project is run out of 4-5 well known observatories, in addition to several hundred astronomers around the globe. This set-up does not lend itself to black -hat covert operations.
The risks of an asteroid or comet impacting the earth of sufficient size to create an extinction level event is around 1 in 1 million years, whereas the risk of one large enough to wipe out a city is rather more frequent , thought to be around 1 every 100 years or so - The recent meteor strike in Russia would be a very good example of that - An amazing phenomenon to see on the various video clips, but must have been pretty frightening if you were on its flight path.
We are not geared up to be able to scan the skies very efficiently though, so there are scenarios where I can imagine a very large meteor on an impact trajectory with Earth being picked up with only days or maybe weeks before it hits, especially if it was coming from a direction we do not tend to scan quite so frequently. In those circumstances, where there was little time to try some sort of planetary defence strategy, I could imagine a government trying to keep a lid on it - the calculation would be the harms that might arise from the panic versus the need for openness and transparency. Thing is , they are not all that good at keeping secrets, especially not in this day and age; And if an attempt was made to defend the planet, that would definitely mean the public became informed.
Not that I am superstitious, but fingers crossed and all that....Our technology and political / cultural development has been such that the one very real human controlled risk - nuclear annihilation through global nuclear war has receded,although an engineered microbe/ virus remains a threat.The others we have very little control over; Large Cometary Strike, Catastrophic Volcanic Eruption (s), A nearby star going supernova emitting gamma radiation. Most of the other risks are longer term, the one causing the greatest debate is Climate Change.
Some Religions, hearing about an imminent extinction level event, ,might attempt to use it as a kind of judgement day, but of course the true judgement day requires a deity and we all know there is no deity, right? ;)
So, talk of "puppetmasters", and "hiding the truth" sound a little - paranoid - to me.