The United States accused Russia on Monday of blocking international inspectors from reaching the site of a suspected poison gas attack in Syria. Washington also said Russians or Syrians may have tampered with evidence on the ground. Russia denies the tampering accusations, and vows to respond if the US imposes new economic sanctions. Jack Parrock has more from Moscow.

JACK PARROCK MOSCOW "Russia says that OPCW chemical weapons inspectors will be going in to the Douma site where this suspected chemical weapon attack took place last weekend on Wednesday. Nikki Haley is saying that the US could impose further sanctions on Russia over that support of the Syrian government. Russian lawmakers here in Moscow have been considering retaliatory sanctions. But we don't expect any announcement on that until May the fifteenth. Really Russia doesn't have the economic bite on the international stage to do anything that could harm the US, nowhere near in the way that the US can harm Russia. Jack Parrock, CGTN, Moscow."