Vice President Biden pledged Thursday that the U.S. was prepared "to impose further costs on Russia" if it does not withdraw support for separatists in Ukraine.
During a phone call with Ukrainian President Petro Poroshenko, Biden said Russia needed to halt the provision of heavy weapons and materiel across the border, according to a readout of the call provided by the White House.
Earlier Thursday, Poroshenko said he was ready to resume a ceasefire agreement if rebel fighters would abide by it and enter into peace talks, according to the ITAR-TASS news agency.
Poroshenko halted military action against the separatists for a week last month in hopes of jump-starting negotiations, but rebels killed 27 Ukrainian servicemen and wounded another 69 during the ceasefire. That prompted the Ukrainian leader to order air and artillery strikes against rebel bases and checkpoints.
Last week, the White House hinted it would move to impose additional economic sanctions if Russia did muscle separatists into a series of concessions by Monday. But pressed on the deadline, White House press secretary Josh Earnest said the administration was still evaluating its options.
The so-called "scalpel sanctions" would narrowly target Russia's technology, defense and financial sectors. The penalties would likely ban U.S. companies and financial institutions from doing business with major Russian banks, prevent technology transfers to Russia’s natural gas industries and block deals with Russian defense companies.
President Obama is scheduled to discuss the crisis with NATO Secretary-General Anders Fogh Rassmussen on Tuesday at the White House.