TOKYO (Reuters) – Japan and the United States agreed on Tuesday on the need for concrete progress at talks this month on ending North Korea”s nuclear arms program, while China sent an envoy to Pyongyang to pave the way for a long-elusive deal.

Communist North Korea agreed over the weekend to return to talks on its nuclear ambitions with the United States, host China, Japan, South Korea and Russia. The meeting — the first since June 2004 — will be held in the week of July 25.

&#34What we really need is a strategic decision on the part of the North that they are indeed ready to give up nuclear weapons because, without that, these talks cannot be successful,&#34 Secretary of State Condoleeza Rice told a joint news conference with Japanese Foreign Minister Nobutaka Machimura in Tokyo.

Machimura told the same news conference: &#34We agreed that concrete progress is necessary and we expect North Korea to make a serious and constructive response.&#34

Reviving the talks has become more urgent because of concerns Pyongyang has expanded its nuclear capabilities to eight or more weapons, up from one or two weapons when President Bush came to office in 2001.

In a sign of the diplomatic push, Chinese State Councilor Tang Jiaxuan, a special envoy of President Hu Jintao, headed for North Korea earlier on Tuesday.

U.S. officials had said earlier that North Korea was calling a nuclear-free Korean peninsula the &#34dying wish&#34 of its late leader, Kim Il-sung, and this might be a way for Pyongyang to explain its decision to return to six-country talks.

But the officials said they had seen no concrete sign the North would surrender its nuclear capability.

Still, after several years of seeking to isolate Pyongyang, Rice said the Bush administration was &#34absolutely willing to negotiate seriously … we are prepared to roll up our sleeves.&#34

Experts say that for the talks to succeed, the five parties other than North Korea must stay united. Officials from Japan, South Korea and the United States will meet in Seoul on Thursday to coordinate their approach.

Differences over what mix of carrots and sticks to use in dealing with Pyongyang have plagued the six-party process.

South Korea said on Tuesday it would give 500,000 tons of rice to the North to help battle a severe food shortage.

The Bush administration has long opposed giving incentives before the North commits to abandoning its nuclear programs and previously urged allies to withhold huge new aid infusions.

But Rice endorsed Seoul”s aid pledge, saying &#34it responds to the really miserable humanitarian situation of the North Korean people (and) does not in any way undercut the (six-party) talks.&#34

She noted that Washington had itself recently promised Pyongyang 50,000 tons of food in aid.

Seoul is planning a major incentive package, which media reports describe as a huge injection of aid akin to the U.S. Marshall Plan that rebuilt western Europe after World War II.

At the third round of talks, in June 2004, the United States proposed fuel aid and security guarantees to North Korea if it gave up its nuclear weapons programs.

While insisting Washington would offer no new incentives to bring Pyongyang back to the table, Rice and other officials now say the 2004 proposal is just a starting position and there was room to alter its terms once serious negotiations start.

Japan, for its part, wants to raise the issue of the abduction of its citizens by North Korea decades ago, a point Machimura reiterated on Tuesday. Pyongyang says the matter is closed and Beijing and Seoul want it to be dealt with separately.

But Rice agreed that abductions — as well as the North”s missile proliferation and human rights records — must be dealt before relations with the North can advance.

But, the nuclear weapons issue is &#34the one that is pressing us in terms of the (six-party) talks,&#34 she said.

The North”s KCNA news agency said the regime had armed itself with nuclear weapons in response to a U.S. threat but &#34we do not intend to possess nuclear weapons forever.&#34

However, former Pentagon official Daniel Bluemthal said in Washington that &#34Pyongyang”s nuclear aspirations go to the core of the regime”s raison d”etre — ensuring its own survival and forcefully unifying the peninsula under its control&#34 and hence it was unlikely that they would be surrendered.