The grim milestone was passed even as figures from the Pentagon showed that the monthly American death toll has fallen for the first time since last August. Fifty-eight American troops died in Iraq in February, down sharply from the month before the January 30 elections and less than half those in last November, the bloodiest month of the conflict for American forces.

Analysts, however, said the fall was less to do with the successful quelling of the insurgency than a shift in targets by the rebels and the gradual withdrawal of American forces from the country’s worst combat zones, leaving Iraqi security forces to take up the slack.

After a lull in violence after the election, in which Shia parties won a majority, insurgents have stepped up attacks against civilians and Iraqi security forces. This strategy, which aims to ignite civil war, is one that many analysts say has become more urgent for insurgents. “They have a window of opportunity before the new government is formed to pursue their wrecking strategy,” a Western diplomat said . “Killing Americans is just a distraction from that.”

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