Israel said its forces fought Hamas gunmen inside the militants’ vast tunnel network beneath the besieged Palestinian enclave of Gaza, seeking to free hostages and to push forward its campaign to wipe out the militant group. …

The tunnels under the cramped enclave are a prime objective for Israel as it expands its ground operations and pushes further into Gaza from the north to hit Hamas in retaliation for the Islamist group’s deadly surprise attack on southern Israel three weeks ago.

Some of the 240 hostages that Israel says were seized by Hamas that day are believed to be held in the tunnel complex, adding a further complication for the Israelis on top of the difficulties of fighting in an urban setting.

[I covered some of this in my earlier post. If Hamas thought that the tunnels would provide them a decisive advantage in a ground war, they’re about to find out that it imposes severe limitations on defense as well — especially if the IDF can collapse the structures at key points. It’s still going to take a lot of bleeding to defeat Hamas in those tunnels, though, especially if they’re trying to find the hostages alive in them. — Ed]