MOSCOW - President Vladimir Putin says Russia may end up having to aim nuclear weapons at Ukraine.
Putin's remarks are the latest salvo in the war of words over the former Soviet republic's attempt to join the NATO military alliance.
Putin says targeting Ukraine with nuclear weapons is frightening to even think about.
But he says it may be necessary if the government in Kyiv accepts the deployment of anti-missile defences on its territory.
Putin spoke at a news conference in Moscow after four hours of talks with Ukrainian President Viktor Yushchenko, who has said joining the western alliance is a priority for his country.
Yushchenko responded at the news conference by saying Ukraine has the right to form its own foreign and defence policies. However, he noted that the Ukrainian constitution does not allow for the deployment of foreign bases on its territory.
"You understand well that everything that Ukraine does in this direction is not in any way directed at any third country, including Russia,'' Yushchenko said.
Last month, Yushchenko, Prime Minister Yulia Tymoshenko and Ukraine's parliament speaker signed a formal request asking NATO to consider Ukraine's bid for a Membership Action Plan at its meeting in Romania in early April.
The membership plan is a crucial step on the road to joining the western alliance.
The Kremlin announced Tuesday that Putin would attend the NATO meeting.
Russia has long been concerned about the alliance's expansion into the former Soviet republics of Estonia, Latvia and Lithuania, as well as former Soviet bloc countries.
In Kyiv, some politicians reacted strongly to Putin's threat.
"We are an independent state and will make our decisions regardless of what others say,'' said former defence minister Anatoly Grytsenko, who is a senior member of Yushchenko's party.
NATO membership is a highly controversial issue in Ukraine, where opinion polls show that more than half the country opposes it.
Also worrying Moscow are U.S. plans to deploy missile defence sites in Poland and the Czech Republic, calling them a threat to that undermines Russia's nuclear deterrent.
