U.S. Secretary of State Hillary Clinton says she regrets Pakistan's withdrawal from next week's international conference on Afghanistan but hopes to secure Islamabad's cooperation in the future.

Clinton told a news conference in South Korea Wednesday that Pakistan, like the U.S., has a “profound interest in a secure, stable and increasingly democratic Afghanistan.”

The top U.S. diplomat said Islamabad and Washington must learn lessons from a NATO air assault that killed 24 Pakistani soldiers in disputed circumstances Saturday so the two countries can continue fighting terrorism together. She pledged a quick and thorough investigation of what she called a “tragic incident.”

Pakistani officials have said they will not participate in next Monday's meeting in Bonn, Germany in protest against the airstrikes.

Afghan President Hamid Karzai also urged Pakistan to reconsider its decision to boycott the talks on his country's future. Mr. Karzai called Pakistani Prime Minister Yousuf Raza Gilani Tuesday, asking him not to turn his back on the conference. The Afghan leader also extended his condolences for Pakistan's losses.

Pakistani military officials say they believe NATO launched the airstrikes intentionally. General Ashfaq Nadeem also questioned whether Pakistan would participate in Washington's investigation into the air assault.

The Associated Press quotes U.S. officials as saying investigators believe the Taliban attacked a U.S.-Afghan patrol in the border region to create confusion and draw U.S. and Pakistani forces into firing on each other.

The Bonn conference is aimed at developing a strategy to stabilize Afghanistan as coalition forces withdraw in the coming years. Many analysts agree that peace in Afghanistan hinges on whether Pakistan plays a constructive role in the process.

The White House calls the Bonn talks very important for the future of Afghanistan and says Pakistan will play a very important role.