N. Korea says U.S. hostility and the threat of American troops in South Korea are important reasons behind its nuclear drive.

For the first time, the trilateral talks will also include military and intelligence chiefs from both Afghanistan and Pakistan.

It was the third major attack in several weeks in or near the northern city, an ethnically mixed area of Arabs, Kurds and Turkmens.

New talks involving all five permanent members of the UN Security Council plus Germany are due soon.