United States President Barack Obama declared in 2009, that America’s nuclear strategy would include a commitment to ‘Global Zero’ – a multinational cooperative effort dedicated to the voluntary elimination of nuclear weapons.

The new approach placed reductions through arms control at the forefront of US policy. The administration’s most notable achievement was the negotiation and ratification of a new Strategic Arms Reduction Treaty - New START - which came into force in 2011.

The agreement between Moscow and Washington included new verification measures, commitments to limits on weapons and delivery systems, and dialogue on ballistic missile defences.

The first bumps on the road to disarmament occurred when Moscow baulked over negotiating future reduction efforts and continued to lodge complaints over Nato ballistic missile defence programmes.

Claims of Russian violations of previous nuclear agreements have soured interest on additional arms control cooperation with Moscow in the US Congress.

The loss of momentum for ‘nuclear zero’ will probably be exacerbated by the current crisis in Ukraine. Not only has the confrontation between Washington and Moscow further poisoned any likelihood of additional arms control negotiations, but some countries will interpret the Russian annexation of Crimea as a strong cautionary argument against de-nuclearisation.

Several countries found themselves in possession of portions of the former Soviet Union's nuclear arsenal after the break-up of the Soviet Union in 1991. Ukraine became the world’s third largest independent nuclear power.

The United States, United Kingdom and Russia sought to placate it over relinquishing its stockpile, signing a pledge in 1994, that the West and Russia would respect Ukraine's national sovereignty and territorial integrity.

Ukraine in turn signed a pact to close nuclear silos and decommission or transfer its nuclear cache to Russia.

Pavlo Rizanenko, a member of the Ukraine parliament, said of their position after the latest confrontation with Moscow, ‘Now there's a strong sentiment in Ukraine that we made a big mistake.’

Additionally, the ongoing ‘final status’ talks between Iran and the P5+1 countries - the five permanent members of the UN Security Council, namely United States, Russia, China, United Kingdom, and France, plus Germany - are unlikely to stem concerns over further global proliferation. Even if a final agreement is signed, the steps Iran would be required to take are reversible.

The deal would not address two other key components of the nuclear weapons programme - the development of a delivery vehicle and long-range ballistic missiles - or limit Iran’s ongoing collaboration with North Korea, potentially the world’s worst nuclear and missile technology proliferator.

Regional powers, including Saudi Arabia and Israel, will still fret over a potential Iranian nuclear breakout.

Many believe both Turkey and Egypt would also contemplate establishing independent nuclear capabilities to match a nuclear-armed Iran.

Venezuela also remains a subject of proliferation concerns. Its government has long sought to establish a civilian nuclear programme and its long-term aspirations remain unclear.

There are also few signs that established nuclear powers will further reduce their programmes.

The six-party talks organised in 2009 to address North Korea's nuclear programme were suspended. Pyongyang announced in 2013 that it would restart all its nuclear facilities, including a uranium enrichment plant at Yongbyon.

The Chinese nuclear programme is growing, shifting from minimal deterrence to limited deterrence, fielding a number of new delivery systems. Its long-term plans are unclear.

The West has little insight into China's nuclear doctrine, especially with regards to neighbouring countries, although China officially abides by a no-first-use policy of not using nuclear weapons against non-nuclear states.

France announced a plan in 2009 to reduce its arsenal to 300 warheads. That reduction went forward. Published French military strategy stated in 2013 that nuclear deterrence remains a vital component of national defence.

The situation is similar in the United Kingdom, which has committed to buy new submarines capable of launching nuclear missiles and the D5 Trident II missile life-extension programme.

Less is known about the future plans of India, Pakistan and Israel, although there is public discussion in these countries about nuclear reductions.

The most likely, and most dangerous, proliferation scenario remains a cascading addition of new nuclear powers in the Middle East as a response to the emergence of a nuclear-capable Iran and uncertainty over US security guarantees for the region.

Look to Pakistan and North Korea as the most likely sources of key weapons and missile technologies.

Proliferation will be matched by a sharp rise in the deployment of ballistic missile defences as countries seek extra ways of ensuring stability and a credible deterrent in a world with more independent nuclear powers.

 - James Jay Carafano, a leading expert in America’s national security and foreign policy challenges, is the Washington-based Heritage Foundation’s vice president for foreign and defence policy.