Question: Battle Extension

[Warmonger]

In a Finland advance, Soviet delay battle the original length was 28 turns. There were three objective clusters; the northern one separated and not defended, the middle and southern one were close together. The southernmost cluster was worth more points than either of the other two clusters. Call the clusters 1 - 3 from north to south.

The Finns dispatched a small force to cluster 1 and made the main assault against cluster 3. By turn 24 the northern cluster was taken. The Finns took about half of cluster 3 by turn 24 and were then counter attacked and the cluster 3 hexes were retaken by the Soviets. On turn 28 the Soviets controlled clusters 2 and 3 and the Finns cluster 1. Of the main Finn attack there were only three remnant squads left. This would have been a minor victory for the Soviets but the game didn't end.

Turn 29 there was minor skirmishing between the Finn remnants and the Soviet defenders. Starting turn 30 the Finn northern force attacked cluster 2 and by turn 33 had taken more than half of the cluster and in the process had been wiped out. At this point the game ended in a draw.

My questions are these:

1. What are the criteria for extending the game?
2. Does it only apply to the attacking force?
3. Shouldn't the defender be given an opportunity to retake objectives during an extension?