As explained in Train Wreck: The U.S. Violation of the Chemical Wreck: The U.S. Violation of the Chemical Weapons Convention (Georgetown Public Law and Legal Theory Research Paper No. 12-128):

The United States is violating a multilateral arms control treaty. Russia is, too. It’s not just some minor accord at stake; it’s the 1993 Chemical Weapons Convention (CWC)...it’s a blatant transgression of one of the treaty’s most fundamental provisions, requiring the timely destruction of the massive inventories of chemical weapons (CW) ... each country will fall years beyond complying with the treaty’s April 29, 2012 final deadline for accomplishing the total dismantling of this noxious ordnance -- the United States now figures to eclipse that mandatory mark by at least 11 years.

The specific treaty is The Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction as ratified by the US Senate 24 April 1997.

As explained in Train Wreck: The U.S. Violation of the Chemical Weapons Convention (Georgetown Public Law and Legal Theory Research Paper No. 12-128):

The United States is violating a multilateral arms control treaty. Russia is, too. It’s not just some minor accord at stake; it’s the 1993 Chemical Weapons Convention (CWC)...it’s a blatant transgression of one of the treaty’s most fundamental provisions, requiring the timely destruction of the massive inventories of chemical weapons (CW) ... each country will fall years beyond complying with the treaty’s April 29, 2012 final deadline for accomplishing the total dismantling of this noxious ordnance -- the United States now figures to eclipse that mandatory mark by at least 11 years.

The specific treaty is The Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction as ratified by the US Senate 24 April 1997.