Since triplea version 1.3.3.0 it is preferred to use relationships instead of or in addition to alliances. If relationships are set, then alliances will only matter for the stats panel and any game option type victory conditions
<attatchment name="relationshipTypeAttachment" attatchTo="War" javaClass="games.strategy.triplea.attatchments.RelationshipTypeAttachment" type="relationship">
<option name="archeType" value="war"/>
</attatchment>
relationship values: a relationship that needs to be present in the game: "player1:player2:relationship" (will set #rounds to -1 by default) OR "player1:player2:relationship:numberOfRoundsThisRelationshipMustExistForMinimum"for example: "Japan:China:War" or "Japan:China:War:-1" or "Japan:China:War:3". It will accept "anyWar", "anyNeutral" and "anyAllied" as well. <attatchment name="conditionAttachmentRussiansNeutralAmericans" attatchTo="Russians" javaClass="games.strategy.triplea.attatchments.RulesAttachment" type="player"><option name="relationship" value="Russians:Americans:anyNeutral"/> </attatchment>