A federal judge in Washington ruled Tuesday that the government was properly holding two Guantánamo detainees as enemy combatants, the first clear-cut victories for the Bush administration in what are expected to be more than 200 similar cases. The ruling by a federal district judge, Richard J. Leon, followed his decision last month in a separate case declaring that five Algerians had been held unlawfully at the detention camp in Guantánamo Bay, Cuba, for nearly seven years and ordering their release.