Bombs killed four NATO troops Monday — two Americans and two Britons — ending the deadliest month of the war for U.S. forces as the top NATO commander called for a new strategy to confront the Taliban.

The U.S. military said the two Americans were killed in separate explosions in southern Afghanistan but gave no further details. Their deaths brought to 47 the number of U.S. troops who have died in the Afghan war in August — three more than in July which had been the deadliest month.

In London, the British Ministry of Defense said the two British soldiers were killed by a bomb on a foot patrol north of Lashkar Gah, a southern Afghan city where Prime Minister Gordon Brown paid a surprise visit last weekend and promised help for his embattled force.

U.S. casualties have been mounting since President Barack Obama ordered 21,000 more American troops to Afghanistan, shifting the focus of the war on Islamic extremism from Iraq to this country where the global conflict began nearly eight years ago.

Since the reinforcements began arriving last spring, American deaths have climbed from six in April to 12 in May, 24 in June to more than 40 for the next two months as U.S. troops push into areas of the country long under Taliban rule.

The latest casualties occurred as the top U.S. and NATO commander Gen. Stanley McChrystal sent his much-anticipated strategic review of the Afghan war to the Pentagon and NATO headquarters.

“The situation in Afghanistan is serious, but success is achievable and demands a revised implementation strategy, commitment and resolve, and increased unity of effort,” McChrystal said in a statement Monday.

U.S. Secretary of Defense Robert Gates ordered the 60-day review to size up the rapidly deteriorating security situation in Afghanistan.

McChrystal did not ask for more troops but is expected to do so in a separate request in a couple weeks, two NATO officials said on condition of anonymity because they were not authorized to speak on the matter.

The U.S. already has about 62,000 troops in Afghanistan — a record number — and will have 68,000 by the end of the year. In total there are more than 100,000 U.S. and NATO troops in the country. There were roughly 250,000 international forces in Iraq during the 2003 invasion.

U.S. officials had hoped that the Aug. 20 presidential election would establish an Afghan government with the legitimacy to combat the Taliban, corruption and the flourishing drug trade.

The vote, however, was clouded by allegations of widespread fraud as well as threats and intimidation by the Taliban.

New vote tallies released Monday showed President Hamid Karzai leading with 45.8 percent of the votes counted, with top challenger Abdullah Abdullah trailing with 33.2 percent. Ballots have been counted from almost half of the country’s voting stations. Karzai needs 50 percent of the votes to avoid a runoff.

On Monday, an Afghan man told reporters that Taliban militants cut off his nose and both ears as he headed for a polling station in central Afghanistan.

“I was on my way to a polling station when Taliban stopped me and searched me. They found my voter registration card,” Lal Mohammad said from a hospital bed in Kabul. He said after cutting him, they beat him unconscious with a weapon.

“I regret that I went to vote,” Mohammad said, crying and trying to hide his disfigured face. “What is the benefit of voting to me?”