U.S. discussing options in response to Russian involvement in Ukraine

WASHINGTON (Reuters) - The United States accused Russia on Thursday of actively fighting in eastern Ukraine in support of separatist forces and said it was considering a range of possible responses including increased sanctions.

"It is clear that Russia has not only stepped up its presence in eastern Ukraine and intervened directly with combat forces, armoured vehicles, artillery, and surface-to-air systems, and is actively fighting Ukrainian forces as well as playing a direct supporting role to the separatists proxies and mercenaries," U.S. State Department spokeswoman Jen Psaki told a media briefing.