Why was Gulliver afraid to be seen near the Blefescu coast?

Gulliver was afraid he'd be discovered by enemy ships if he was too near the coast.

The empire of Blefuscu is an island situated to the north-east of Lilliput, from which it is parted only by a channel of eight hundred yards wide. I had not yet seen it, and upon this notice of an intended invasion, I avoided appearing on that side of the coast, for fear of being discovered, by some of the enemy’s ships, who had received no intelligence of me; all intercourse between the two empires having been strictly forbidden during the war, upon pain of death, and an embargo laid by our emperor upon all vessels whatsoever.