KIEV, Ukraine (CNN) -- A planned missile defense system in Eastern Europe poses no threat to Russia, President George Bush said Tuesday, responding to concerns that the U.S. might use interceptor missiles for offensive purposes.
President Bush, with President Viktor Yushchenko, praised Ukraine's democratic and military reforms.
"The missile defense system is not aimed at Russia," Bush said at a news conference in Kiev following talks with the Ukrainian president. "It's viewed as an anti-Russian device. Well, it's not."
His comments came before he left Kiev for a NATO summit in Bucharest, Romania, that is expected to highlight divisions over the plan. The summit begins Wednesday.
Russia and some European countries have expressed concerns about the missile defense system. While Poland and the Czech Republic have agreed to host parts of the system, others in Europe share Russian concerns that the defensive shield could be used for offensive aims.
Outside the U.S. Embassy in Kiev on Monday, protesters gathered to denounce Bush's visit. They chanted, thrust signs into the air -- one reading, "Yankee Go Home" -- and burned an effigy of Bush in the street. Watch the demonstration »
The U.S. has tried to dissuade opposition over the plan. Washington offered to allow Russian monitors at the missile sites and to negotiate limits to the system over time. The United States also told Russia the system would not be operational until Iran test-fires a missile that could threaten Europe.
Many European countries don't believe the U.S. assertion that the system is needed to guard against imminent threats from Iran or North Korea. Europe is dependent on Russia for at least 40 percent of its oil and is reluctant to upset the Kremlin.
The issue will likely be divisive at this week's three-day NATO summit, where Russian President Vladimir Putin plans to make a rare appearance. Putin normally declines invitations to attend.
Bush is slated to meet Sunday with Putin in the Russian resort city of Sochi on the Black Sea, according to RIA Novosti. It will be the last meeting between the two men before the outgoing Russian president steps down, the Russian news agency reported.
Russia also is unhappy with NATO's eastward march. The alliance has already welcomed former Soviet republics such as Latvia, Lithuania and Estonia. Bush is pushing hard for Georgia and Ukraine to join NATO as well.
Before leaving Tuesday for Bucharest, Bush said that Russia will not be able to veto Georgia's or Ukraine's inclusion into NATO.
Bush said that both countries should be able to take part in NATO's Membership Action Plan, or MAP, which is designed to help aspiring countries meet the requirements of joining the alliance.
"I strongly believe that Ukraine and Georgia should be given MAP," Bush said. "And there's no tradeoffs, period."
The U.S. president further said he was working "as hard as I can" to ensure the two countries are accepted into the MAP and that Russia will have no power to block their inclusion.
In remarks last month, former U.S. Ambassador to Ukraine Steven Pifer told the U.S. Commission on Security and Cooperation in Europe that NATO "has long made clear that any decision regarding membership is between NATO and the country concerned, and not subject to veto by any third party."
Russia is not a NATO member but works with the alliance via the NATO-Russia Council. Russia's concerns also align with those of some NATO members who oppose welcoming Georgia and Ukraine into the fold.
Pifer said last month that NATO should strive to maintain good relations with Russia, but "should not allow Moscow a veto, either explicit or tacit, over relations between the alliance and third countries."
Allowing Russia a say, Pifer said, "would encourage those in Russia who wish to reassert a Russian-led post-Soviet bloc rather than develop a relationship of cooperation and full partnership with Europe and the West."
Bush said he phoned Putin recently to reassure him on both issues.
"NATO is an organization that's peaceful. NATO is an organization that helps democracies flourish. And democracies are good things to have on your border," Bush said he told Putin.
Ukrainian President Viktor Yushchenko said his country should be able to start the NATO membership process.
"We are not speaking about joining NATO; we are only speaking about MAP," he said at the news conference. "Why should Ukraine be deprived of that sovereign right, since the principle of open doors is the basic principle for NATO?"
Bush added that Ukraine already contributes to NATO missions, specifically in Iraq, Afghanistan and Kosovo. Ukraine also has demonstrated a commitment to democracy, he said.
Responding to a reporter's question, Bush denied that the United States might ease off on membership plans for Ukraine and Georgia if Russia acquiesces on the missile shield.
Both issues threaten to destabilize NATO, said Jane Sharp of the Center for War Studies at King's College London, but she has heard particularly sharp criticism of the missile defense plan.
"Somebody in the UK Ministry of Defense said to me, 'We are being dragged along on this missile defense thing to the American trough like pigs with rings in our noses,'" Sharp said. "It's a nuisance for Europeans, and I think they are irritated with the Czechs and the Poles for trying to do deals with the Americans." E-mail to a friend