An armored train believed to be carrying North Korean leader Kim Jong-il was spotted heading to the Russian border on Tuesday evening. Diplomatic sources in Seoul said U.S. and South Korean intelligence officials confirmed that the armored train left Pyongyang and headed toward Hamgyong Province, and Kim was expected to meet Russian President Dmitry Medvedev in Vladivostok. But the train never crossed the border, according to a source.

Kremlin spokeswoman Natalya Timakova Wednesday told reporters Medvedev would attend several events during his trip to Vladivostok but no summit was scheduled with Kim. "President Medvedev will preside over a meeting covering the preparations for the APEC Summit in 2012 and tour facilities and a bridge on Ruski Island [off Vladivostok] that are being built for the summit," Timakova said.

Japan's NHK TV had quoted Russian officials as saying authorities in the Siberian port were preparing to welcome Kim and his entourage. South Korean government officials believed Kim is seeking to normalize ties with Russia amid frisson with China and icy relations with Seoul.

When Russia denied a summit was scheduled, Japan's Kyodo news agency said Kim's ailing health caused the trip to be canceled. But South Korean officials believe the reason was disagreements over the agenda. "If North Korea decided not to hold a summit, it must have been due to disagreements with Russia," said one South Korean official. "North Korea is seeking to gain concessions, but Russia may have demurred."

South Korean and U.S. intelligence officials believe there is still a chance that Kim could visit Russia during Medvedev's trip to Vladivostok. "The Russian spokeswoman said no summit was scheduled, but she didn't say there would be no summit," said one.

The last time Kim met a Russian leader was at a summit with then-president Vladimir Putin in August 2002.