NATO says two of its soldiers were killed in southern Afghanistan late Sunday, the same day America's top military officer said the situation in the country is "serious and deteriorating."
In a televised interview with CNN, the chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, said the Taliban insurgency has become more sophisticated in its tactics.
Mullen also said in a separate interview he is worried about waning American public support for the Afghan war.
In July, international forces suffered their highest death toll, 76 troops, since the war began in late 2001. On Monday, Estonia said that two its soldiers serving with NATO forces in Helmand province were killed by a roadside bomb Sunday.
The New York Times also reported Sunday that U.S. military commanders with the NATO mission in Afghanistan say they do not have enough troops to do their job.
The newspaper did not identify its source, but said commanders emphasized to U.S. special envoy Richard Holbrooke in recent meetings that they needed more troops.
Holbrooke met with military officials at all four regional command centers in Afghanistan.
The report comes as the Obama administration awaits an assessment from its commander in Afghanistan, General Stanley McChrystal, on the current situation. That review is expected in the next two weeks.
Meanwhile, the main challenger in Afghanistan's presidential election, former Foreign Minister Abdullah Abdullah, accused President Hamid Karzai's campaign of widespread fraud.
The Karzai campaign has denied the allegations, and accused the Abdullah campaign of fraud.
The Afghan Electoral Complaints Commission says it has received 225 claims of fraud, including charges of ballot stuffing and voter intimidation.
The Independent Election Commission, which counts the vote, says it will begin releasing partial results Tuesday.
Both Mr. Abdullah and Mr. Karzai have claimed victory. If no candidate wins more than 50 percent of the vote, a runoff election will be held.
Some information for this report was provided by AP and Reuters.