The destruction of Syria's chemical weapons stockpile is well underway, and the agency overseeing it – the Organization for the Prohibition of Chemical Weapons – has won a Nobel Peace Prize.

But despite global praise and a smooth start, the mission faces difficult challenges, from tight deadlines to safety risks for inspectors trying to get to sites near fighting. There's also political fallout. The decision to make Syrian President Bashar al-Assad a partner in destroying the stockpile appears to have restored some of his legitimacy and boosted his chances of staying in power longer, while angering his opponents who now balk at attending political transition talks the U.S. hopes will begin in November.

What happens next for the OPCW?

  • Syria became a full member of the OPCW on Monday.
  • By Oct. 27, Syria must submit a plan for the destruction of its stockpile.
  • On Nov. 1, OPCW inspectors must complete verification of the inventory and render production, mixing and filling facilities unusable.
  • By Nov. 15, the OPCW must adopt a plan for destroying the stockpile, aiming for completion by mid-2014.

How big is Syria's chemical arsenal?

Syria has briefed the OPCW, which is not releasing the information. The UN says Syria has about 1,000 tonnes of chemical weapons materials. Former OPCW official Ralf Trapp and disarmament expert Jean-Pascal Zanders said Syria has about 300 tonnes of sulphur mustard, a blistering agent, and about 700 tonnes of the nerve agents sarin and VX. The OPCW won't say how much of the nerve agents are weapons-ready, but suggests much is in a precursor form, as separate components.

How dangerous is the mission?

Sixty OPCW inspectors and UN staff are on the ground and the team is to grow to 100. The OPCW chief told the BBC that one abandoned site was in rebel-held territory and routes to others led through it, preventing access.

The UN is to arrange safe passage for inspectors, but rebels have not promised co-operation. The risks were illustrated when regime warplanes bombed the rebel-held town of Safira last week, near one of the likely chemical weapons facilities. Over the weekend, two mortar shells struck 300 metres from the Damascus hotel where the inspectors are staying.

How realistic is the timetable?

Trapp, Zanders and Smithson said destroying munitions and machinery with blow torches, sledgehammers and bulldozers by Nov. 1 is achievable. Destroying the chemical arsenal will be more complicated. Steven Bucci, a former U.S. defence official, said the target dates are "wildly optimistic," noting that it is taking the U.S. and Russia decades to destroy much larger stockpiles.

Trapp and Zanders said Syria's chemical weapons threat can be eliminated relatively quickly once the mustard gas, the weapons-ready nerve agents and the means of delivering them are all destroyed.

How will the stockpiles be destroyed?

By Nov. 1, inspectors are to have visited each site, taken photos, tagged and sealed items and destroyed specialized production equipment and unfilled munitions.

In the next phase, the chemicals themselves will be destroyed. Neutralization with chemical agents is preferred, the OPCW said, and that chemical precursors – the ingredients that when combined form weapons-grade chemical compounds – are easier to destroy than weapons-ready materials. Mustard gas, for example, can be neutralized with strong alkaline water or bleach.

Mobile units will likely be deployed for some of the destruction, but some parts of the arsenal may be shipped out of the country, Trapp and Smithson said.

Is the regime co-operating?

The OPCW needs Syrian co-operation to destroy the stockpiles, and the mission could falter if the regime collapses before mid-2014.

U.S. Secretary of State John Kerry said the regime deserves credit for "complying rapidly," though he insisted Assad has lost the legitimacy to rule.

Smithson, of the Center for Nonproliferation Studies, a U.S. think-tank , said the regime appears to be co-operating but has a "very sorry track record" on working with nuclear inspectors. She said it is easier to hide chemical and biological weapons than a nuclear program but that satellites would likely detect serious attempts to cheat.

Under the OPCW's rules, the Syrians would have to allow inspection of any site that raises suspicions.

Who else has chemical weapons?

North Korea, Angola, Egypt and South Sudan haven't signed the convention. Israel and Burma have signed but not ratified. North Korea is believed to have 3,000 to 5,000 tonnes of chemical weapons materials, Zanders said, adding that he is not aware of a chemical warfare capacity in either Egypt or Israel.

Seven countries have declared stockpiles: Russia, the U.S. India, Albania, Libya and a "state party" believed to be South Korea. The U.S. and Russia started out with a combined stockpile of more than 70,000 tonnes and have so far destroyed about 80 per cent.