WASHINGTON -- The Obama administration has quietly arranged for thousands of chemical protective suits and related items to be sent to Jordan and Turkey and is pressing the military forces there to take principal responsibility for safeguarding Syrian chemical-weapons sites if the country’s lethal nerve agents suddenly become vulnerable to theft and misuse, Western and Middle Eastern officials say.

As part of their preparations for such an event, Western governments have started training the Jordanians and Turks to use the chemical gear and related detection equipment, so they’re capable of protecting the Syrian nerve-agent depots if needed – at least for a short time, U.S. and other Western officials say.

Washington has decided, moreover, that the best course of action in the aftermath of Syrian President Bashar Assad’s possible fall would be to get the nerve agents out of the country as quickly as possible, so it’s begun discussions not only with Jordan and Turkey, but also with Iraq and Russia to chart the potential withdrawal of the arsenal and its destruction elsewhere.

The Obama administration regards using allied forces from Syria’s periphery as the most likely “first responders” to a weapons-of-mass-destruction emergency as a way to avoid putting U.S. troops in the region if the special Syrian military forces now safeguarding the weapons leave their posts. A Syrian withdrawal otherwise might render the weapons vulnerable to capture and use by Hezbollah or other anti-U.S. or anti-Israeli militant groups, U.S. officials fear.

This article is based on conversations about international planning for the disposition of the Syrian stockpile with a half-dozen U.S. and foreign officials who declined to be named because of the sensitivities surrounding their work. They said the Western planning, while not yet complete, was further along than officials had publicly disclosed.

So far, the Turkish and Jordanian governments haven’t promised to take up the full role that Washington has sought to give them, U.S. and foreign officials said.

Jordanian Embassy spokeswoman Dana Zureikat Daoud said the training under way was “not mission-oriented,” meaning that Jordan doesn’t have a fixed responsibility. But she added that the government is concerned about the possibility of Syrian chemical armaments falling into extremist hands. “Our contingency plans . . . are discussed and elaborated with like-minded, concerned countries,” she said.

A spokesman at the Turkish Embassy declined to comment. James F. Jeffrey, the U.S. ambassador to Turkey from 2008 to 2010, said that although Ankara was eager for the United States to play a larger role in resolving the Syrian crisis, the Turks were “usually reluctant to be our foot soldiers.” He added: “When Americans come up with a plan to use country X’s soldiers, the plan is often self-fulfilling inside the Beltway,” but it sometimes runs into trouble when it’s broached in foreign capitals.

Worries about the fate of the chemicals – in a stockpile estimated at 350 to 400 metric tons (385 to 440 short tons) – have become so great that Washington and its allies have recently passed messages to some of the Syrian commanders who oversee their security, offering safety and a continued role under a new government if the commanders act responsibly, two knowledgeable officials said.