The Russians must show they are not pursuing a "sham game" to thwart US efforts to establish missile defense sites in Europe, but the two sides may be closer to agreement for cooperation on the planned shield, US officials said Monday. Speaking to reporters en route to the Russian capital from Washington, US Defense Secretary Robert Gates said he and US Secretary of State Condoleezza Rice saw some prospect of progress on long-stalled negotiations over US proposals to establish missile defense sites in central Europe. But he did not sound particularly optimistic. "I wouldn't get too enthusiastic at this point," he said. Setting a tough tone even before arriving, Gates questioned the sincerity of the Russian government's objections to missile defense. "My view is we've put a lot on the table" in recent negotiations, Gates said. "Now it's time for them to reciprocate." Gates was joined a short time later by Rice, who traveled separately. Rice would not predict a breakthrough but said Russia may be more convinced of the shield's utility, and that the two sides see opportunities for technical collaboration. "I would hope that we can move from the conceptual level to some more specific proposals," Rice told reporters flying with her to the joint meetings. Without offering specifics, Rice indicated that the two sides are nearer to an arrangement to assess and plan side-by-side for theoretical missile threats from such rogue states as Iran or North Korea, and for ways to assure Russia that the shield is being developed and deployed as advertised. That could include both human and electronic monitoring of sites planned for Poland and the Czech Republic, Rice said. "We can certainly have enough bridging of that so that they and we have some confidence that a missile defense shield is really aimed at that threat," Rice said. Gates and Rice were to meet President Vladimir Putin and President-elect Dmitry Medvedev on Monday before daylong talks the next day with the Russian defense and foreign ministers. The sessions come five months after a similar engagement in Moscow that produced no discernible progress toward agreement. Gates said he and Rice were bringing no new missile defense proposals to the talks, which will cover a wide range of topics, including cooperation against terrorism, future arms control talks and economic relations. US officials have said they have "tweaked" previous proposals for cooperation that got a mixed reaction from Moscow. Rice, the top US diplomat, suggested the Russians are watching the US election season with an eye to cutting a deal, or at least making headway while there is a known commodity in the White House. In general, she said, "people want to get as much done as they can, because they sense American politics are going to be unpredictable." During the in-flight interview, Gates was asked whether he thinks the Russians genuinely object to US missile defense sites in Europe on security grounds, as they have insisted for months. "Truth is, I don't really know," he said. "I don't know whether there are genuine concerns on the part of the Russians that we can allay and where we can be partners," or whether their counterproposals for sharing radars and other suggestions are "all basically a stalling exercise" by the Russians. "At some point the Russians are going to have to decide whether they want to be true partners - which we're offering - or whether this is all just a sham game on their part to [stop] the whole deal," he added. In an interview published Monday, Russian Deputy Foreign Minister Alexander Grushko rejected the suggestion that the installations would not pose a threat to Russia's nuclear deterrent. "All our estimates show that the system the US wants to deploy in Poland and the Czech Republic, already in its current configuration, will have a significant negative effect on our forces of deterrence," Grushko told the daily Nezavisimaya Gazeta. "This would introduce a factor of uncertainty in the strategic balance between Russia and the US." The Bush administration is negotiating with Poland to establish a base there for 10 missile interceptors. They would be linked to a radar site in the Czech Republic, if the Czech government agrees. The system would be part of a wider network of interceptors, radars and communications sites in the United States and elsewhere for defending the United States and its allies against long-range missiles. In their meetings in Moscow in October, Gates and Rice said the Bush administration would consider delaying activation of the proposed sites in Poland and the Czech Republic until hard evidence is in hand regarding Iran's development of a ballistic missile capable of reaching Europe and beyond. The Russians have not accepted that proposal. Gates said Monday the offer is still on the table.