WASHINGTON — The Pentagon said late Friday that Russian aircraft had entered Ukrainian airspace "on several occasions in the last 24 hours" and called on Moscow to take "immediate steps" to de-escalate rising tensions.
The air incursions, which officials said may have been part of an effort to test Ukraine's radar, took place as tens of thousands of Russian troops, massed on Ukraine's southern and eastern borders for weeks, began "military drills" announced Thursday.
As skirmishing continued in eastern Ukraine between government forces and pro-Russia militants, the halting U.S.-European effort to impose new sanctions on Russia picked up speed amid a flurry of calls among top government leaders and agreement that last week's deal with Moscow to calm the crisis was all but dead.
European Union foreign ministers planned to meet Monday in Brussels to approve new asset freezes and visa bans on at least 15 prominent Russians close to President Vladimir Putin and deemed responsible for the deteriorating situation in Ukraine, a European official said.
The United States held off announcing new sanctions as President Barack Obama called the leaders of Britain, France, Germany and Italy to confirm they were on the same page.
"We will have to act," German Chancellor Angela Merkel said, "and I think this will be a common European action and a joint action of the G-7 states." The Group of Seven leading world economies also include Canada and Japan.