Ukraine handed its former Soviet nuclear arsenal to Russia in the 1990s in exchange for assurances that the Kremlin would respect Ukraine's sovereignty.
Now some experts are asking whether Russia's annexation of Crimea might undermine efforts to prevent the spread of nuclear arms.
According to French Foreign Minister Laurent Fabius, Russia's occupation of the Black Sea peninsula unequivocally violates the 1994 Budapest Memorandum — an official pledge signed by the Russian Federation, the United States and Britain — to respect Ukraine's territorial integrity and political sovereignty.
Both China and France provided similar assurances in 1994.
Meeting with Brazil's foreign minister, Fabius said the situation may discourage nuclear powers from giving up their arsenals, and persuade those without nuclear weapons to acquire them in order to protect their territory.
According to James Goldgeier, Dean of the American University School of International Service in Washington, Moscow's violation of the agreement could have a chilling effect on nonproliferation efforts.
"You're basically sending a signal to every other country out there to think twice about either giving up nuclear weapons or not pursuing them in the first place, because if Ukraine had a nuclear deterrent, you wouldn't see the Russians moving against Ukraine," he said.
Daryl Kimball, who leads the Arms Control Association, says Budapest was not a Western commitment to protect Ukraine's sovereignty by force. Still, he says Russia's actions could mean trouble.
"But I think, you know, this incident, if it's not addressed properly by the United States and Russia and our allies in Europe, could shake confidence in the security assurances that are issued by the nuclear arms P-5," he said, referring to the five permanent members of the United Nations Security Council.
Ukraine did not want to keep its nuclear weapons anyway, according to John Haines of the Foreign Policy Research Institute, who spoke to VOA from Philadelphia via Skype.
"This was an arsenal that was in a poor state of repair, that was going to be difficult to maintain, and that probably posed more of a domestic risk within Ukraine than its deterrent effect on any other nation," he said.
Kimball says other countries that could abandon nuclear weapons will base their decisions on other factors as well.
"Those countries that could potentially eliminate their nuclear arsenals, including North Korea, are going to do so on the basis of arrangements that go well beyond a political document that provides some sort of security assurances," Kimball said, adding that the impact Russia's annexation of Crimea will have on global nonproliferation efforts remain to be seen.