However, its role has since been transformed to prevent North Korean ships heading south.

These calm periods often prevented ships from getting to shelter in time.

Britain used its navy to prevent American ships from trading with France.

They were there to prevent Swedish ships to get to and from Greifswald.

These forts prevented British ships from taking shelter in the harbour.

The new location was easier to defend as the reefs prevented ships from approaching the city except at high tide.

Sediment, however, has clogged a lot of the river channel above this point, preventing big ships from going any farther.

I can prevent ships from landing, but I can't make them come.

The pirate can also prevent ships from being built or moved nearby, but it does not interfere with harbors.

But months of continuing operations to prevent ships from hitting mines lie ahead.