MOSCOW — North Korean leader Kim Jong Il's armored train reportedly arrived Tuesday in an eastern Siberian city for a summit with Russian President Dmitry Medvedev as Russian military officers flew to Pyongyang for military talks.

Kim is expected to meet Medvedev this week near the Russian city of Ulan-Ude for talks that could focus on a natural gas pipeline deal. It is Kim's first visit to his country's Cold War ally in nine years. North Korea is also pushing to restart six-nation nuclear disarmament talks in exchange for aid, after more than a year of tension during which it shelled a South Korean border island and allegedly torpedoed a South Korean warship.

Kim arrived Tuesday morning in Ulan-Ude, the capital of Buryatia, a Buddhist province near Lake Baikal, South Korea's Yonhap news agency reported; he then got into a car with people waiting at the station and went toward the city. Yonhap said the Medvedev-Kim summit is expected to take place Wednesday but did not elaborate.

Russian military officials, meanwhile, arrived in the North Korean capital on Monday for a five-day visit, the ITAR-Tass news agency reported from Pyongyang. The Russian Defense Ministry said the talks will focus on the renewal of military cooperation between the countries, possible joint exercises "of a humanitarian nature" and an exchange of friendly visits by Russian and North Korean ships.

Military expert Alexander Golts said North Korea's goal could be to assuage fears of instability as Russia considers building a natural gas pipeline through North Korea. The pipeline is expected to be one of the main topics of Kim and Medvedev's talks.

Golts said it was highly unlikely Russia would renew arms sales to North Korea, which would not be in its interests as a participant in the six-nation nuclear talks.

In Washington, State Department spokeswoman Victoria Nuland said that Russia — as "a partner in the six-party talks" — shares the view we all have: "In order to get back to the talks, we need an improvement in North-South relations, and we need the (North) to show concrete steps toward denuclearization."

She said that "one would hope and expect that if we have the leader in Russia, that these points are being made to him."

Kim's train crossed into Russia on Saturday morning and passed through Khabarovsk before heading west along a railway running roughly parallel with Russia's borders with China and Mongolia. The itinerary for his visit, expected to last about a week, has been largely kept secret because of what appears to be high security concern from North Korea.

But the Korea Herald newspaper stated bluntly a strain of thinking in Seoul in an editorial Tuesday: "It does not take genius to guess why North Korean leader Kim Jong Il is visiting Russia. Kim desperately needs economic aid."

The North, which has long experienced chronic food shortages, has been hit with heavy flooding in recent weeks.

Kim was seen during a stop Sunday at the small Bureya station in Amur province. Flags of the two countries fluttered at the railway station, while a military band played welcoming music and Russian women in national dress offered Kim traditional gifts of bread and salt.

Kim then was taken in his armored Mercedes for a tour of a hydroelectric power plant and its 139-meter (456-foot) dam on the Bureya River. He was briefed on the plant's history and electricity production capacity and praised the enormous building, the North's official Korean Central News Agency reported from Pyongyang.

"Inexhaustible is the strength of the Russian people," Kim wrote in the visitor's book, KCNA said.

Russia has proposed transmitting surplus electricity produced by the Amur plant to both North and South Korea, South Korean media have reported.

South Korean President Lee Myung-bak, while on a visit to Mongolia, said that "if (Kim) frequently visits and looks at an open society, that will eventually positively affect North Korea's economic development," spokesman Park Jeong-ha said, according to South Korea's Yonhap news agency.

A Russian regional news agency, PortAmur, posted photographs showing the 69-year-old Kim wearing his trademark Mao-style khaki jumpsuit. In all but one of the photographs he is seen wearing dark sunglasses. He traded them for regular eyeglasses when presented with a framed picture as a gift.

The Amur.info news website reported Monday that people living near the Bureya rail station were told to stay away from windows and prohibited from taking pictures. The local residents, however, were grateful for the makeover of the station's square, which was newly paved for Kim's visit, the website said.

Kim's train traveled along the Trans-Baikal Railway.

There were signs that preparations were being made for Kim to visit the village of Turka, on the shores of Lake Baikal. The Baikal Daily website quoted residents as saying that a local police officer had been making the rounds to take down the names and addresses of all the people in the village.

One key topic for Medvedev and Kim's talks is expected to be the construction of a pipeline that would stream Russian natural gas through the North's territory to the South. South Korea media said the North could earn up to $100 million every year, but negotiations haven't reported much progress because of the nuclear dispute.

Officials from Russia's state-controlled natural gas giant Gazprom visited North Korea in early July for talks on the gas pipeline. North Korean officials at the time reacted positively to the project, a change from a previous reluctant position, according to South Korea's Foreign Ministry.

The JoongAng Ilbo newspaper, however, raised worries Monday that the North could abruptly shut down the gas supply depending on relations with the South.

"As long as there is the possibility that the gas supply would be interrupted by the North for political or military reasons, it is difficult for Seoul to put a final stamp on the deal," the paper said in an editorial.

North Korean diplomats separately met U.S. and South Korean officials last month to discuss the resumption of the nuclear talks, which have been stalled for more than two years.

Kim traveled to China in May in a trip seen by many as an attempt to secure aid, investment and support for a transfer of power to his youngest son Kim Jong Un. It was Kim's third visit to his country's closest ally in just over a year.

Hyung-jin Kim, Foster Klug and Jiyoung Won reported from Seoul, South Korea.