HELSINKI, Finland: It was not the most auspicious of starts for a U.S.-Russia summit. President Bill Clinton, suffering from a bad knee injury, arrived in Helsinki in an airline catering truck, carefully lowered from Air Force One to accommodate his wheelchair. Meanwhile, Russian President Boris Yeltsin descended the steps of his plane with the painfully stiff cadence of a man who has spent nearly a year in and out of hospital bed. The two leaders will find little relief from their suffering in the two-day summit that kicked off today. Conceding that the major headache, NATO expansion toward Russia's borders, is not likely to disappear anytime soon, both Clinton and Yeltsin preferred to downplay expectations that the summit would result in a major breakthrough. "It's not the goal of this summit to reach some concrete agreement," Kremlin spokesman Sergei Yastrzhembsky said in Helsinki, adding that, instead, Yeltsin and Clinton would aim simply for a higher "level of mutual understanding." Clinton echoed the Russian viewpoint, telling reporters that he would pursue a "relationship that makes Russia a true partner of the (NATO) alliance." The two leaders put out their first feelers on NATO at a state dinner at the Finnish presidential palace. Eager to win Moscow's complaisance with NATO membership for former Warsaw Pact countries Hungary, Poland and the Czech Republic (scheduled for 1998), the U.S. has offered Russia membership in a joint council that lets it peek in on NATO decisions without exercising a veto. To sweeten the deal, Washington has also said it will reduce NATO weapons stockpiles beyond the limits set by the Conventional Forces in Europe treaty, while offering additional cuts in long-range nuclear weapons. While Yeltsin presumably won't pass up on the offer, his opposition to installation of NATO forces or facilities on former Warsaw Pact territory remains firm. In recent days, Yeltsin has also made clear his opposition to what will be an even bigger hurdle for the West: expanding NATO to include former Soviet republics Estonia, Latvia and Lithuania as well as longtime satellite Finland.