Seoul, April 01 (Saba) - U.S President Barack Obama on Thursday reaffirmed Washington''s commitment to providing Seoul with an "extended nuclear deterrence" against any possible North Korean attack in a phone conversation with South Korean President Lee Myung-bak, according to Qatar News Agency (QNA).

Obama also said the U.S. will fully assist South Korea''s troubled search for 46 missing sailors believed to be trapped in a sunken warship and an investigation into the cause of the tragedy that happened last Friday, according to South Korea''s News Agency (Yonhap).

"President Lee and President Obama discussed the North Korean nuclear issue and other pending issues in an international telephone call this morning," a South Korean presidential official said.

"President Obama said the U.S. remains committed to an extended nuclear deterrence for South Korea."

During the phone call, made at the request of Obama, the two leaders also discussed the Nuclear Security Summit to be held in Washington later this month.

Saba