U.S. military officials said Russian aircraft flew into Ukrainian airspace several times Friday.
A Pentagon spokesman called on Moscow “to take immediate steps to de-escalate the situation.” The official gave no details on where the incursions took place or the goal of the action.
The flights come as Russia increases military exercises along the Ukrainian border. On Thursday, the top U.S. military officer Chairman of the Joint Chiefs of Staff, General Martin Dempsey, spoke with his Russian counterpart.
Also Friday, pro-Russian separatists in eastern Ukraine detained a team of international military observers. The separatists seized a bus carrying at least 13 people from the Vienna-based Organization for the Security and Cooperation in Europe [OSCE] near the town of Slovyansk.
The town’s self-declared mayor, Vyacheslav Ponomarev, said the group was detained because a Ukrainian military official was traveling with them.
“The sign OSCE does not mean protection for an officer of the [army] General Headquarters. We found an employee of the army headquarters. After an investigation we will decide what we are to do,” said Ponomarev.
The OSCE wrote on Twitter that it had lost contact with the German-led monitoring team.
The United States and the European Union are expected on Monday to impose new sanctions on Russian individuals, sources said, as the Ukraine crisis escalated with armed pro-Russia separatists seizing a bus carrying international mediators.
The U.S. State Department is condemning the reported abduction of an international observer team and its Ukrainian escorts by armed gunmen in the town of Slovyansk.
“If true, we strongly condemn this action and call for their immediate release,” said State Department spokesperson Jen Psaki. “Over the past week, we’ve unfortunately seen a rapid escalation in hostage takings by pro-Russian separatists. We condemn this repressive and cowardly tactic and call for the release of all hostages.”
Pro-Russian separatists say the group was detained because a Ukrainian military official was traveling with them.
The interior ministry in Kyiv said the detained group includes seven OSCE representatives and five members of the Ukrainian armed forces who were accompanying them.
On his Twitter account, Swedish Foreign Minister Carl Bildt called for the group’s immediate release: “Extremely concerned with OSCE inspectors being abducted in Eastern Ukraine. Including one Swede. They must be released immediately.”