BRUSSELS, Belgium — It's a grim gauge of U.S. wars going in opposite directions: American and allied combat deaths in Afghanistan passed the toll in Iraq for the first time last month.

Defense Secretary Robert Gates used the statistical comparison to dramatize his point to NATO defense ministers that they need to do more to get Afghanistan moving in a better direction. He wants more allied combat troops, more trainers and more public commitment.

More positively, the May death totals point to security improvements in Iraq that few thought likely a year ago.

But the deterioration in Afghanistan suggests a troubling additional possibility: a widening of the war to Pakistan, where the Taliban and al-Qaida have found haven.

By the Pentagon's count, 15 U.S. and two allied troops were killed in action in Iraq last month, a total of 17. In Afghanistan it was 19, including 14 Americans and five coalition troops. One month does not make a trend, but in this case the statistics are so out of whack with perceptions of the two wars that Gates could use them to drive home his point about Afghanistan.

Even when noncombat deaths are included, the overall May toll was greater in Afghanistan than in Iraq: a total of 22 in Afghanistan, including 17 Americans, compared with 21 in Iraq, including 19 Americans, according to an Associated Press count.

The comparison is even more remarkable if you consider that there are about three times more U.S. and coalition troops in Iraq than in Afghanistan. Since the Iraq war began in March 2003, there have been just under 4,100 U.S. deaths — including more than 3,300 killed in action — according to the Pentagon's count. In the Afghan campaign, which began in October 2001, the U.S. death total is just over 500, including 313 killed in action.

"It's important that we live up to our pledges in both the civilian and military spheres as necessary for success in Afghanistan," Gates said Friday, concluding two days of NATO defense minister talks that produced few signs of optimism about the Afghan war.

Gates made a point upon taking his Pentagon post in December 2006, amid great and growing U.S. public doubt about Iraq, that he was deeply concerned about backsliding in the less publicized and less unpopular war in Afghanistan.