UNITED NATIONS (AP) — The U.S. ambassador to the United Nations on Thursday accused Moscow of having “outright lied” about its role in Ukraine, as alarmed members of the Security Council demanded that Russia remove its fighters from a new front in the unfolding crisis and threatened sanctions.

A top U.N. official told the emergency meeting that the spread of violence in southeastern Ukraine marked a dangerous escalation, but that the international body had no way of independently verifying the latest reports of Russia sending in troops and tanks.