If the Obama administration wants an example of the difficulties involved in destroying chemical weapons, it might reflect upon its own struggles to get rid of cold-war era chemical arsenals stockpiled in tightly controlled storage facilities in Kentucky and Colorado.

The United States promised, but failed, to destroy these stocks by 2012 at the very latest. The most recent forecast from the US is that the process of "neutralising" the chemicals in its Colorado weapons dump will be finished by 2018; the date for Kentucky is 2023. That will be 11 years after the US promised to destroy its chemical weapons stockpiles, and eight years after Russia – the other major possessor of declared chemical weapons – says it will have finished destroying its arsenal.

About 2,611 tons of mustard gas remains stockpiled in Pueblo, Colorado. The second stockpile, in the Bluegrass region of Kentucky, is smaller – 524 tons – but more complicated to decommission, because it consists of a broader range of lethal gases and nerve agents, many of which are contained within weaponry.

Although the process of constructing neutralisation facilities in Colorado and Kentucky is well under way, both plants have still not begun testing procedures. The nature of the Kentucky stockpile makes it particularly difficult to destroy.

"They have every agent there and every weapon – rockets, artillery shells, landmines, spray tanks and aerial bombs," said Paul Walker, a program director at Green Cross International, which has facilitated the destruction of chemical weapons in the US and Russia since the mid-1990s.

Syria claimed this week that it would sign its chemical weapons over to international control, kickstarting a process that could lead to the destruction of the type of nerve agents that were alleged to have been used by the regime in suburbs outside Damascus on 21 August.

The proposal, endorsed by Russia, has been seized on by the White House as a diplomatic path that would avert military strikes, but doubts have been raised about the technical practicalities of securing Syria's chemical weapons and then destroying them.

The secretary of state, John Kerry, is flying to Geneva on Thursday for a two-day meeting with his Russian counterpart, Sergey Lavrov. The State Department said both diplomats would bring specialists to the meetings to discuss the "mechanics" of a programme of Syrian chemical weapons destruction.

The US and Russia have struggled to decommission their own stockpiles of weapons, built-up during decades of confrontation during the cold war. The process has taken place under the auspices the Chemical Weapons Convention – the same treaty Syria has now pledged to commit to.

Enforcement of the convention is overseen by the Organisation for the Prohibition of Chemical Weapons (OPCW), which is based at The Hague. The OPCW provided the scientists who conducted recent United Nations weapons inspections in Damascus and, if Syria were to commit to destroying its stockpiles, would oversee and verify the process.

US chemical weapons stockpile in Kentucky. Photograph: US Army Chemical Materials Activity

Kerry and Obama have repeatedly referred to enforcement of the "norms" enshrined in the 1993 convention as a justification for military strikes. In total, 189 countries are now members of the chemical weapons convention.

Syria is one of seven countries that have not ratified the convention; the others are Angola, South Sudan, Burma, Egypt, North Korea and Israel.

However, even those countries that have not signed the treaty are arguably bound by the broader international norm against production, stockpiling or use of chemical weapons.

Since the late 1990s, the US has made great efforts to destroy its own chemical weapons caches, and facilitating the process in the handful of other so-called "possessor states" – in some cases helping fund the process through aid.

However, technological and political challenges have resulted in lengthy delays. By missing its deadlines, the US and other countries have arguably breached a founding principle of the same treaty cited as a reason to justify an attack on Syria.

When the convention came into force in 1997, participating countries agreed to destroy their stockpiles within 10 years, with an option to apply for a five-year extension. Five countries – the US, Russia, South Korea, India and Albania – all missed the main 2007 deadline.

Two years ago, the United States, Russia and Libya were granted further extensions to a previously agreed final deadline for destroying their weapons.

The process in Libya has been complicated because Muammar Gaddafi is believed to have concealed small, secretly stockpiled stashes of weapons that may not have been destroyed. Iraq is controversially proposing to encase and bury its chemical weapons stockpiles as a cheaper alternative. Other countries such as North Korea and Israel are suspected by some of possessing chemical weapons but have not declared them.

However, the majority of declared, undestroyed chemical weapons remain in Russia and the US. The US has destroyed 90% of the chemical weapons it declared in 1993, when the treaty was first signed.

The final stretch of weapons destruction has been beset by technological developments, political challenges and lawsuits. If the US finally meets its promise of destroying all chemical weapons by 2023, the process will have taken more than a quarter of a century and cost an estimated $40bn.

The process could be further delayed further by sequestration, the process of automatic budget cuts affecting the Pentagon, which has promised to prioritise work that relates to combat readiness over less urgent projects.

Russia is scheduled to complete its destruction of chemical weapons stockpiles by 2015, eight years before the US. "It is clear that while Russia and the US have violated the convention, in the sense that they have not met the agreed deadline for destroying all chemical weapons in their countries, those delays are understandable," Walker said. "The failure to meet these arbitrary stockpile destruction deadlines should not discredit their complete commitment to destroying their remaining stockpiles."

Echoing the remarks of other experts, Walker said the process of destroying Syria's stockpile of chemical weapons could take up to a decade and cost several billion dollars.

The precise size and nature of Syria's stockpile is unknown, but is likely to be far smaller than the 30,000 tons the US declared in 1990. The secretary of state John Kerry said on Tuesday that Syria possessed 1,000 tons of chemical agents, most of it in the form of unmixed binary components stored in tanks.

India and South Korea, which have destroyed similar-sized stockpiles, took about three or four years to destroy their weapons, but that process only began after the lengthy process of building the plants that were used to destroy the chemicals.

There is little international doubt that there was a chemical weapons attack in Syria on 21 August, which US intelligence officials say killed more than 1,400 people. The US and its allies allege the Syrian government was behind the attack – a charge denied by Bashar Al-Assad and publicly questioned by Russia.

However, the Assad regime has since implicitly admitted it possesses the weapons.

Weapons destruction, a technologically complicated and risky process, is determined by the types of chemical agents, their location and whether or not they have been "weaponised". The process will take considerably longer in a country such as Syria, and could also be made more complicated because the Syrian stockpiles are believed to be stored in several locations.

Analysts say it is unlikely Syria would have the funds to pay for the programme itself, although under the treaty the obligation would be born by the Syrian government. "We may be talking two or three billion," Walker said. "I think the US would be willing to step up to the plate. But that is just a guess."

The US already spends $500m to aid other countries in nuclear, biological and chemical weapons destruction around the world, via one congressionally-authorised programme. Russia, Germany, France, the UK or Canada might also be expected to contribute to any weapons destruction process.

A spokesperson for the US Department of Defense, which oversees and pays for the destruction of chemical weapons stockpiled in the US, said that in 2011 states that were party to the OPCW "acknowledged the need for additional time for the United States, the Russian Federation, and Libya to destroy their chemical weapons".

Under the new extension, a spokesperson said there would be "continued international monitoring of the stockpiles, additional transparency measures, information reporting, and periodic site visits at destruction facilities".