Impoverished North Korea has spent an estimated 700 million dollars this year on nuclear and missile tests, enough to solve its food shortage for at least two years, according to South Korean news reports.
The figure includes the estimated 43 million dollar cost of test-firing five Scud and two Rodong missiles Saturday, according to unidentified government officials quoted by Chosun Ilbo newspaper, reported AFP.
The latest tests, staged on the US Independence Day holiday, were seen as a show of defiance to Washington as it seeks tough enforcement of UN sanctions aimed at shutting down the communist state's nuclear and missile programmes.
Officials quoted by Chosun estimated it cost 300 million dollars to launch a long-range Taepodong-2 missile on April 5, and another 10 million to launch 10 short-range missiles in recent weeks.
In addition, they estimated the May 25 underground nuclear test -- the country's second since 2006 -- cost between 300-400 million dollars.
JoongAng Ilbo gave similar figures. Neither paper gave the methodology for the cost calculation.
Chosun quoted an unidentified official as saying the North could have bought one million tons of rice on the international market for 300 million dollars.
"This amount of rice could have solved the North's food shortage for about a year," the official was quoted as saying.
The United Nations World Food Programme has said that according to a study last year, nearly nine million North Koreans -- more than a third of the country's 24 million people -- are estimated to need food aid.
Saturday's launches were the biggest salvo of ballistic weaponry since the North fired a Taepodong-2 and six smaller missiles in 2006, also on July 4 US time.
US Vice President Joseph Biden on Sunday dismissed the launches as "like almost attention-seeking behaviour" and said the focus was on further isolating Pyongyang.
"We have succeeded in uniting the most important and critical countries to North Korea on a common path of further isolating North Korea," he told ABC television, referring to Russia and China.
These have been traditionally resistant to tough sanctions on Pyongyang but backed the latest measures approved on June 12.
US and South Korean officials believe ailing leader Kim Jong-Il, 67, is staging a show of strength to bolster his authority as he tries to put in place a succession plan involving his youngest son Jong-Un.
Speaking on CBS television Sunday, the top US military commander fretted about the "unpredictability" of the regime.
"I'm very comfortable with our defensive posture, that we can protect our interests, our people and our territories," Joint Chiefs of Staff Chairman Mike Mullen said.
"What I am increasingly concerned about is just the belligerence and the unpredictability of the North Korean leadership," Admiral Mullen said.
The chief nuclear negotiators from Japan and South Korea held talks in Seoul Monday on the North Korean nuclear issue and the weekend missile tests.
Wi Sung-Lac and Japan's Akitaka Saiki "had in-depth discussions on the North Korean nuclear issue including the implementation of the UN Security Council resolution and the next step", said foreign ministry spokesman Moon Tae-Young.
The North quit six-nation nuclear disarmament talks in April in protest at the Security Council's decision to censure its rocket launch earlier that month.