KABUL, Afghanistan – Ten NATO service members, seven of them Americans, were killed in separate attacks Monday on the deadliest day of the year for foreign forces in Afghanistan. A U.S. civilian contractor who trains Afghan police also died in a suicide attack.

The bloodshed comes as insurgents step up bombings and other attacks ahead of a major NATO operation in the Taliban stronghold of Kandahar that Washington hopes will turn the tide of the war.

Half the NATO deaths — five Americans — occurred in a single blast in eastern Afghanistan, U.S. spokesman Col. Wayne Shanks said. It was a grim reminder that insurgents can strike throughout the country — not simply in the south, which has become the main focus of the U.S. campaign.

Two other U.S. service members were killed in separate attacks in the south — one in a bombing and the other by small arms fire.

NATO said three other service members were killed in attacks in the east and south. The French government said one of the victims was a sergeant in the French Foreign Legion who was killed by a rocket in Kapisa province northeast of Kabul. Three other Legionnaires were wounded.

The American police trainer and a Nepalese security guard were killed when a team of three suicide bombers attacked the main gates of the police training center in the southern city of Kandahar, U.S. officials said.

Afghan officials said one bomber blew a hole in the outer wall, enabling the two others to rush inside, where they were killed in a gunbattle. Afghan officials said three police were wounded.

It was the deadliest day for NATO since Oct. 26, when 11 American troops were killed, including seven who died in a helicopter crash in eastern Afghanistan.

U.S. commanders have warned of more casualties as the alliance gears up for a major operation to secure Kandahar, the former headquarters of the Taliban and the biggest city in the south with 500,000 people.

Last December, President Obama ordered 30,000 U.S. troops to Afghanistan to try to stem the rise of the Taliban, who have bounced back since they were ousted from power in the 2001 U.S.-led invasion.

As fighting escalates, the Afghan government is reaching out to the insurgents in hopes of ending the nearly nine-year war. Last week, President Hamid Karzai won endorsement from a national conference, or peace jirga, for his plan to offer economic and other incentives to the militants to lay down their arms, and to seek talks with the Taliban leadership. The leadership has so far publicly shunned the offer, and branded Karzai a U.S. puppet.