US State Department spokeswoman Heather Nauert said Tuesday Russia has to stop bombardment in Syria's eastern Ghouta.
Nauert added that Syrian Dictator Bashar Al-Assad had shelled schools and hospital in eastern Ghouta with the support of Russia and Iran.
She also urged Moscow to claim responsibility for the poisoning of a former spy and his daughter in London earlier this month.
On Tuesday, the United States and its European allies expelled dozens of Russian diplomats in a co-ordinated response to the poisoning of a former Russian spy in the UK.
It is said to be the largest collective expulsion of Russian intelligence officers in history.
More than 20 countries have aligned with the UK, expelling more than 100 diplomats.