By Joyce Lee and Jack Kim SEOUL, Feb 26 (Reuters) - North Korean leader Kim Jong Un said he would focus on expanding his country's nuclear arsenal and that prospects for improving relations with the U.

SEOUL, South Korea (AP) -- North Korean leader Kim Jong Un was reelected to the top post of the ruling Workers' Party, with delegates crediting him for bolstering the country's nuclear arsenal and strengthening its regional standing, state media reported Monday.