Dave,
Of course my other sources are top secret so you just have to trust me that they are right.

I do not trust you or Putin, but when the evidence is so powerful as to convince every EU nation, plus Canada, Australia, the US and all the other well informed liberal democracies in the world, plus the Labour Party's leadership, I trust.

Only a delusional political fanatic would believe all those decent nations are involved in a lying conspiracy over this.