Of No Defence Significance

OK, I'm sure many of you have heard this phrase a lot. It seems to be the standard reply to unusual phenomena reported to the Ministry of Defence in the UK.
In this instance I'd like to draw attention to two cases, hopefully ones that the debunkers will look at and run a mile.

The first was over the North Sea on the 5th November 1990, as a squadron of Tornado fast jets was casually overtaken by a UFO. A full report was made by the pilots, but the case was dismissed as having "No defence significance". Hang on a minute! Our best fighter jets of the time, the ones we go to war with, are overtaken in flight by a UFO and it is of no concern to our powers that be, the very ones responsible for the defence of our realm? Unbelievable.

The second event I want to mention goes like this:

On 31st March 1993, a UFO flew directly over two military bases; it was seen by a guard patrol at RAF Cosford and by the meteorological officer ar RAF Shawbury, who described it as being a triangular shaped craft only marginally smaller than a Boeing 747. It flew over the base at a height of about 200 feet, was making a low humming sound and was seen to fire a beam of light at the ground. It was moving very slowly, but suddenly shot off at several times the speed of a fast jet. Nothing was detected on radar.

Source: A Covert Agenda

Again, the MoD stance on this is that it was "Of no defence significance". That these objects can traverse our airspace with impunity and outrun our best fighter jets of the time shows massive technological advancement. Either the MoD knows what they are and allows them to be here, whether alien in nature or secret terrestrial aircraft, or the other alternative, one that I pray to my gods isn't the one, is that they really are not concerned.

What are your thoughts on this?

a quick google search will yield pages of results on what i would consider a defence threat from ufos. How many times have we heard about ufos that hover over munitions (nuclear) bunkers, beaming bright lights directly at them. Eyewitnesses are usually all military of some sort and are all wondering what can come and go so freely around such high security nuclear weapons.
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If this isn't a security threat i dont know what is. Weather its ET or not doesnt matter really, the fact that this type of thing has happened repeatedly with no major reaction from the US government or other governments of the world is a bit creepy