Chinese and North Korean defence chiefs have pledged to strengthen their long-standing military alliance, BBC reported.
The Chinese Defence Minister, Liang Guanglie, is visiting North Korea two weeks before the US North Korea envoy, Stephen Bosworth, is due to visit.
North Korea's neighbours and the US and trying to re-start talks on the ending of Pyongyang's nuclear programmes.
China has been a firm ally of the North since they fought together in the Korean War against the South.
Analysts have noted, however, that China appears increasingly willing to push the boundaries of its special relationship with the North to support the nuclear talks.
Blood ties
China fears a huge influx of refugees if the North Korean state collapse, and has little desire to see a nuclear-armed state with an uncertain political succession on its border.
Mr Liang told a reception by Pyongyang's defence chief Kim Yong-chun that the bilateral relationship was "sealed in blood" when he and other Chinese troops fought the Korean War on the North Koreans' side.
"No force on earth can break the unity of the armies and peoples of the two countries and it will last forever," Mr Liang said, according to KCNA, the North Korean news agency.
"It is the fixed stand of the Korean army and people to invariably consolidate and develop the DPRK (North Korea)-China friendship, which has stood all trials of history," Kim Yong-Chun said.
The defence chiefs then had "comradely and friendly" talks, according to the report.
Mr Liang arrived in Pyongyang by plane on Sunday, inspected an honour guard, attended a fete, presented a gift for North Korean leader Kim Jong-Il, and met Kim Yong-chun.
Chinese state media has said that Mr Liang would be going on to Japan and Thailand after his North Korean visit.
China has hosted the six-party nuclear negotiations, including delegates from the two Koreas, China, the US, Russia and Japan, since 2003.
China's President Wan Jiabao recently visited Pyongyang and reported that the North was "willing to attend multilateral talks, including the six-party talks, depending on the progress in its talks with the United States".
US President Barack Obama was recently in Beijing, South Korea and Japan where he and his hosts all affirmed the importance of getting North Korea back into talks.