Able to blockade someone under 1000 land

[Ceremony]

My target was Ashenkine.

Area of Influence: 961.226 mile diameter.

549.132 in purchases, -24.433 in modifiers, 436.527 in growth

He has 0 soldiers, 0 tanks, 0 ships, 0 everything.

However, today at update I was able to blockade him with my navy.

To: Ashenkine From: Ceremony Date: 8/27/2008 12:00:20 AM

Subject: Naval Blockade

Message: A naval blockade has been placed against your nation. This blockade will reduce your next tax collection by 5.00%. Together with any previous blockades your next tax collection will be reduced by a total of 20.71%. Any existing peace offers that were on the table have been automatically canceled.

Is this a bug that I was able to do so? Ashenkine is under 1000 land and has no ships.

EDIT: He'll have even less land after this post as I'll be launching a nuke.

EDIT2: I was also able to use battle support against Ashenkine:

To: Ashenkine From: Ceremony Date: 8/27/2008 12:10:32 AM

Subject: Nuclear Attack

Message: Your nation has been attacked with nuclear weapons by Ceremony. You lost 0 soldiers, 0 defending tanks, 0 cruise missiles, 259.909 miles of land, 86.636 technology, 259.909 infrastructure, and 75% of your aircraft and nuclear vulnerable navy force. In addition to these losses your nation will experience many days of economic devastation.

Edited August 27, 2008 by Ceremony

[Lord Emares]

I would imagine its the fact that the nation has an event that drops his land below 1k...and the navy calc isn't taking that into account...