What kept Melkor from attempting a direct Valinor attack?

[BalrogRingDestroyer]

I know that he and Ungoliant did destroy the trees and run off with the Simarils, but, as far as I know, he never tried, even through minions, to attack it directly after that.

Sauron, however, in the Second Age, did, by his attempt to have Numenor invade Valinor. Why did Melkor never bother to go after Valinor directly or via minions?

 

[Valandil]

Fear of losing the Silmarils, I think.

 

[Squint-eyed Southerner]

And fear of the other Valar -- the destruction of the Trees happened while they were away at festival, remember. Their combined power was too great for him to face at once, as was shown in the later war that saw him ejected into the Outer Darkness.

Sauron's goal in corrupting the Numenoreans was their destruction, leaving him in unchallenged possession of Middle Earth; he himself had no illusions that they posed any real threat to Valinor. His "error", if it could be called that, was in failing to consider the possibility that the Valar might "lay down their rule" of Arda, leading to direct intervention by Eru, and his own destruction (temporary though that proved).

 

[Miguel]

a process which was not observed until the later ages - is due to the Marring of Arda, and comes of the Shadow, and of the taint of Melkor that touches all the matter (or hroa)(8) of Arda, if not indeed of all Eä.