Russian President Dmitry Medvedev has praised talks with his Polish counterpart as the start of a "new level" in relations.
The two-day visit comes after an already dramatic improvement in ties this year in Moscow's long-antagonistic relations with Warsaw.
Speaking at a news conference with Polish President Bronislaw Komorowski after the signing of a package of deals over trade, legal cooperation, and Baltic Sea pollution, Medvedev said their talks constituted the first serious dialogue between both sides "in a long time."
"These talks took place in an atmosphere of trust, which may be the most important thing because trust -- beginning with trust between two presidents and ending with trust between societies -- is crucial for developing relations between two peoples," Medvedev said.
The recent political warming between Moscow and Warsaw is evident in closer economic ties. Trade has jumped 40 percent this year to nearly $15 billion as both economies have started to recover from the global financial crisis in 2008. Poland depends on Russian natural gas for two-thirds of its supplies, and the two sides signed a major gas deal earlier this fall.
Medvedev called the talks an "intensive start" to cooperation on economic, humanitarian, and other ties.
"I hope this is just the beginning of full-fledged, mutually advantageous, modern economic ties between our countries," the Russian president said.
Medvedev was also scheduled to speak to Prime Minister Donald Tusk, whose election three years ago laid the groundwork for the current rapprochement.
The turning point came earlier this year, when Prime Minister Vladimir Putin joined Tusk at a ceremony marking the killing of more than 20,000 Poles -- mostly top military officers -- by Soviet forces in Russia's Katyn Forest in 1941.
Three days later, Polish President Lech Kaczynski and many other top Polish officials died when their plane crashed near the Russian city of Smolensk en route to another Katyn ceremony. Poland welcomed Russian cooperation and public sympathy at the time.
Speaking to Polish media ahead of his visit in statements broadcast by Russian state television, Medvedev said he wants relations between Russia and Poland to continue moving to a "new level."
"It's extremely important to leave behind a historical paradigm in relations between Russia and Poland formed a long time ago, and to try to separate whatever took place in history from daily life," Medvedev said. "Otherwise we'll always remain hostage to actions that took place before our time."
Soon after Medvedev's arrival, the two presidents had agreed to jointly oversee the creation of a memorial to Kaczynski and the 95 other Poles who died in Smolensk.
Outside the presidential palace, dozens protested what they said was Russia's lack of transparency in an investigation into the crash. They held signs reading "Smolensk. We want the truth."
Polish and Russian experts have been conducting two separate investigations into the crash. During his news conference, Medvedev said he and Komorowski would personally oversee the investigations, the results of which must be made public.
In his interview with Polish media, Medvedev said it was important for Russia to "clean out the cellars of the past" by "speaking the truth" about Soviet crimes such as the Katyn massacre.
On December 3, Komorowski said he hoped Medvedev's visit would mark a further breakthrough in relations. "I count on this being a new chapter in Polish-Russian cooperation, God willing," he said, "and the start of reconciliation."
But Komorowski warned Medvedev's visit wouldn't be a "one-time event."
"We have a long march ahead of us," he said.
'A New View'
Russia has recently sought to improve its image with Poland and other countries after Medvedev said last spring that Moscow should show a "smiling face" instead of "gnashing teeth" to the world.
Asked in his interview why Moscow had pressed the "reset" button in relations with Warsaw, Medvedev said the decision would have had to been made "sooner or later."
"But such changes have to take place not only in Russia," Medvedev said. "To move our relations to a new strategic, forward-looking level of partnership, changes also have to take place in Poland. There has to be a new view of the new Russia."
Ties between the two countries reached their lowest recent levels under former President Kaczynski, a right-wing nationalist and a fierce critic of Russia, whose brother Jaroslav Kaczynski preceded Tusk as prime minister.
Russia banned meat imports from Poland and fiercely opposed Warsaw's decision to host components of a U.S. missile-defense shield. Those plans have subsequently been changed.
Russia and NATO agreed in November to cooperate on new plans for a missile-defense system and other security issues. But in an interview with Polish weekly "Wprost" ahead of his visit, Medvedev said NATO must fully involve Russia in the alliance's missile shield or risk triggering a new arms race.
Moscow's fragile relations with Warsaw have long been soured by memories of the Soviet Union's invasion of eastern Poland in 1939 following the signing of a Soviet-Nazi pact dividing control over the country. Moscow for decades refused to acknowledge the KGB's role in the Katyn massacre, which the Kremlin blamed on Nazi forces during World War II, an issue that remains deeply painful for Poles.
Prime Minister Tusk was the first Polish leader to be invited to attend official ceremonies marking the Kaytn massacre this year.
Last month, the Russian parliament acknowledged for the first time that Soviet dictator Josef Stalin was responsible for the Kaytn killings.
Moscow has also gradually released Kremlin archive documents related to Katyn, including the latest batch on December 3.
The antagonisms affected Moscow's broader relations with the European Union, which Poland joined after breaking way from the Soviet Bloc in 1989.
written by Gregory Feifer, with agency reports