Officials in northern Afghanistan say a suicide bomber on a motorcycle has killed at least 13 people, including three U.S. troops, and wounded more than 25 others.

Local officials said the attacker detonated his explosives Wednesday in Maimanah, the capital of Faryab province, as the troops were filming interviews at a local park.

The Taliban claimed responsibility for the attack.

So far this year, nearly 100 international troops have been killed in Afghanistan. Violence continues as coalition forces have begun withdrawing from Afghanistan and transferring security responsibility to their Afghan counterparts.

Also Wednesday, Afghan President Hamid Karzai met with the head of U.S. Central Command, General James Mattis, to discuss a wide range of issues, including situation in Afghanistan and the need for a continued support of the Afghan National Army.

Mr. Karzai said the army must be professional and apolical and expressed hope that the international community will continue to help equip, train and finance the country's security forces.

General Mattis said the United States was committed to helping Afghanistan in this respect.

Also present were Afghan Defense Minister General Rahim Wardak and National Security Advisor to the president, Rangin Dadfar Spanta.

The United States and Afghanistan are also pushing toward completion of a long-term strategic agreement defining the U.S. presence in Afghanistan once all foreign combat troops leave the country by 2014.

The issue of coalition night raids has been an obstacle to the agreement. President Karzai has called for an end to such operations, saying they result in civilian casualties and are an invasion of privacy. NATO says the raids are effective in capturing insurgents.

Late Tuesday, U.S. defense officials said the two sides are close to a deal that would allow Afghan forces to take the lead in night raids, with Afghan judges issuing warrants for the operations.

U.S. officials want a deal in place before next month's NATO summit in the U.S. city of Chicago focusing on the future of Afghanistan, including the cost and size of maintaining Afghan security forces.

Afghanistan's minister of commerce and industry, Anwar-ul-Haq Ahadi, told VOA he is “optimistic” his country will get a positive response from NATO on support for its security needs.

“I think there's been already discussion of $4.1 billion annual assistance to our security forces and I'm quite hopeful that this will get endorsed in Chicago so that for the next 10 years we will have a more reliable source of funding to support our security forces.”

He said he expects a similar response from a conference in Tokyo in July, and that both gatherings will have an important role in the future of Afghanistan.