Shamil Basayev, the one-footed and elusive Chechen guerrilla commander who has become Russia’s most-wanted man, has taken responsibility for planning acts of terror that killed more than 440 people since August, and he is threatening more attacks, a separatist Web site said today. In a letter posted on the Internet early today, Mr. Basayev said his group, the Riyadus-Salakhin Reconnaissance and Sabotage Battalion of Chechen Martyrs, “had carried out a number of successful combat operations on the territory of Russia.”Full Story