Russia's annexation of Crimea from Ukraine has left many observers fearing that Washington and Moscow are headed towards a new Cold War. It is not surprising, then, that the crisis has spawned plenty of chatter about one of the Cold War’s most recognizable features: nuclear weapons.

Most of the discussion on this subject has focused on whether Ukraine was wrong to have returned to Russia some 2,000 nuclear warheads left in Kiev’s possession after the collapse of the Soviet Union. Another area of focus has been whether the United States should respond by withdrawing from threat-reduction efforts like New START and increasing the role of nuclear weapons and missile defense against Russia in US and NATO policy. (In this writer’s opinion, the answers are no and no.)

The more interesting and difficult-to-answer question about the Ukraine crisis, though, is whether and how Russia’s Crimean land grab might impact other states’ decisions on whether to acquire nuclear weapons.

In the 1994 Budapest Memorandum, Kiev received assurances—though not a military guarantee—from the United States, the United Kingdom, and Russia that in return for surrendering all former Soviet nuclear weapons, Ukraine’s sovereignty and territorial integrity would be respected. Now that Russia has run roughshod over these assurances, will North Korea’s resolve to maintain and expand its nuclear arsenal be strengthened? Will Iran, now engaged in negotiations with the West on constraining its nuclear capabilities, be less likely to agree to stringent constraints on its nuclear weapons capability in return for a package of incentives that could include a US security assurance? And might US allies begin to question whether they can rely on Washington’s guarantees of protection—and come to see possessing nuclear weapons as more attractive?

Many observers have answered yes to these questions, but the impact of the current crisis on nonproliferation is complex.

For one thing, much will depend on reactions. The United States is not going to war with Russia over Ukraine. However, failing to respond at all to Russia’s blatant violation of international law would send the dangerous signal that states that reject nuclear weapons, or give them up as Ukraine did in return for security assurances, can’t count on outside assistance or support in the face of aggression. Meaningful political, diplomatic, and economic assistance and limited military aid are necessary to support Ukraine, punish Russia, deter future acts of aggression against other US allies and partners, and uphold the credibility of security assurances as a nonproliferation tool—even if it doesn’t reverse Moscow’s illegal annexation.

To date, the United States and European Union have expelled Russia from the G8 and imposed two rounds of sanctions that include freezing assets, banning a group of high-level officials from entering the United States, and preventing a large Russian bank from doing business in US dollars. The US Congress passed legislation approving $1 billion in loan guarantees to support Ukraine’s struggling economy. On the security front, the White House has sent a small number of troops and fighter aircraft to the easternmost NATO members. NATO announced the suspension of cooperation with Russia and ordered the drafting of measures to reinforce its defenses. Some observers are calling for additional security steps along these lines.

But standing up for Ukraine could cut two ways. For example, steps to punish Moscow run the risk of threatening important US-Russian cooperation on other nonproliferation goals, such as strengthening the security of Russian nuclear materials and maintaining a unified front in negotiations between the P5+1 (Britain, China, France, Germany, Russia, and the United States) and Iran. This may be a risk worth taking, but it’s a risk nonetheless.

Meanwhile, as western observers are focused on the impact of the Crimea crisis on non-proliferation incentives and the credibility of security assurances, there is another recent case that bears on these issues: Libya. In 2003, Libyan leader Muammar Qaddafi agreed to give up his nuclear weapons program in return for normalizing relations with the West. In 2011, an internal revolution, aided significantly by western military power, overthrew Qaddafi’s regime.

For the countries of greatest proliferation concern to the United States—namely North Korea and Iran—Libya is likely more relevant to their thinking about nuclear weapons than Ukraine. On one hand, Ukraine’s plight could reinforce their view that weak states that give up nuclear weapons or nuclear weapons capability will be left defenseless. On the other hand, however, North Korea and Iran are concerned primarily by the threat to their security posed by the United States and its allies and partners. As Iran’s Supreme Leader Ayatollah Khamenei put it: “This gentleman [Gaddafi] wrapped up all his nuclear facilities, packed them on a ship and delivered them to the West and said, ‘Take them!’” He added: “Look where we are, and in what position they are now.”

With Gaddafi’s 2011 ouster fresh in leaders’ memories, North Korea and Iran are unlikely to be moved by a strong US response to Russian aggression against Ukraine, or take seriously any future US security assurances.

This brings us back to the question of whether the Ukraine and Libya examples will lead to more nuclear weapons development. The disincentives to further proliferation remain strong. While it will be incredibly difficult, if not impossible, to convince the current North Korean regime to give up its nuclear weapons, Pyongyang pays a high price for possessing them, as a pariah state that is almost totally cut off from the rest of the international system. Likewise, the steps Iran has taken to advance its nuclear program have resulted in punishing economic sanctions, cyber attacks against its nuclear facilities, and threats of military action by the United States and Israel. A move by Iran to acquire nuclear weapons would almost certainly invite a US or Israeli preventive attack, unless Iran could find a way to develop an arsenal in secret (which is unlikely). Likewise, a US ally or partner considering withdrawal from the Nuclear Non-Proliferation Treaty would imperil its alliance with the United States.

Plus, states that might think nuclear weapons will keep them safe also have to wrestle with the paradox that nuclear weapons don’t deter certain types of aggression. Just ask India and Israel, each of whom have been repeatedly harassed—and in Israel’s case even attacked—despite possessing nuclear weapons. Indeed, it’s not at all clear that Ukraine could have prevented Moscow from gobbling up Crimea even if it had nuclear weapons.

What, then, does the above discussion tell us about how the Crimea crisis will affect nuclear proliferation? If the United States and its allies respond forcefully while avoiding unnecessarily counterproductive actions, such as withdrawing from New START, it can minimize the damage to security assurances as a nonproliferation tool. However, the United States shouldn’t expect North Korea and Iran to be moved by US support for Ukraine. And if any countries feel newly motivated to acquire nuclear weapons, they will find that the disincentives and obstacles to proliferation remain formidable.