June could become the deadliest month for coalition forces in the nearly nine-year-old war in Afghanistan.
Violence over the weekend puts the June death toll for coalition troops at 57, including 35 Americans.
Early Monday, a military helicopter crashed in southern Afghanistan, killing three Australians and one American.
Over the weekend, explosions rocked the war fronts in Afghanistan and Iraq.
In Baghdad, a wave of bomb attacks killed at least 27 people.
In Afghanistan, two bombs killed more than 20 people in one of the country's most dangerous provinces.
The latest round of violence shows the enormous difficulties U.S. and its allies face in trying to bring peace to the region, before security details are left in the hands of local forces.
"It is a tough pull and we are suffering significant casualties," saud Defense Secretary Robert Gates.
A United Nations report released on Saturday offered a grim assessment of security in Afghanistan.
It noted that roadside bombings and assassinations soared in the first four months of the year, amid ramped up military operations in the Taliban-dominated south.
But NATO spokesman Josef Blotz told reporters that forces are on the right track, and have stepped up the pace in identifying the killers.
"Tough fighting is expected to continue, but the situation is trending in our favor as more forces flow into the area," Blotz said.
The Obama administration also echoed that theme this weekend, saying progress is being made in Afghanistan.
"About a half of the al Qaeda leadership has been eliminated in this last 18 months," said White House Chief of Staff Rahm Emanuel on Sunday.
Emmanuel also said that the timetable for withdrawing U.S. troops from Afghanistan next July is still in place.