KABUL, Afghanistan — The U.S. military's top officer assured Afghan President Hamid Karzai on Saturday the new NATO commander will pursue the same war strategy crafted by Gen. Stanley McChrystal — the ousted general whom Karzai warmly praised for training Afghan security forces and reducing civilian casualties.

Adm. Mike Mullen visited Afghanistan three days after President Barack Obama accepted the resignation of McChrystal, the commander of U.S. and NATO forces. Afghan leaders and U.S. allies in the war worried his firing could disrupt the counterinsurgency strategy at a critical juncture in the war, but were relieved to learn that his replacement would be Gen. David Petraeus, McChrystal's boss who help author the plan.

During their meeting, Karzai lauded McChrystal, saying he was able to "reduce civilian casualties, create good cooperation between the Afghan and international forces and strengthen and develop the Afghan forces," according to a statement from the Afghan presidential palace.

Karzai welcomed Obama's decision to appoint Petraeus, a man he said had a wealth of experience and knowledge about the situation in Afghanistan, the statement said. Mullen, who later traveled to neighboring Pakistan, assured Karzai that Petraeus would also do his best to reduce civilian casualties, bolster cooperation among the forces and train Afghan police and soldiers.

On the battlefield, three international service members, including at least one American, were killed Saturday in two separate roadside bombings in southern Afghanistan, NATO said. That brought to 87 the number of international troops killed so far in June — already the deadliest month of the nearly nine-year-old war. The figure includes at least 51 Americans.

In a speech earlier in the day marking International Narcotics Day, Karzai acknowledged that curbing Afghanistan's huge drug trade remains a major challenge, despite success in reducing or eradicating opium poppy cultivation in 22 of the country's 34 provinces.

"We will work strongly against poppies and other narcotics for our national interest, honor, the welfare of Afghan people and development," he said. But he said the problem will not be solved until other countries crack down on smugglers within their own borders who profit from the traffic in Afghan poppies and heroin.