U.S. Secretary of State John Kerry has accused Russian President Vladimir Putin of destabilizing Ukraine through "land grabs," saying that Moscow and the rebels have failed to observe a cease-fire agreed earlier this month.
Kerry's comments to U.S. lawmakers on February 25 came amid a lull in the fighting in eastern Ukraine, with Kyiv saying that no deaths had been reported on the front for the first time since the truce took effect 10 days ago.
But there was still no confirmation, from the Organization for Security and Cooperation in Europe (OSCE), of a pull-back of heavy weapons from the frontline -- the other key provision of the deal reached in Minsk on February 12.
"To date, neither Russia nor the [separatist] forces it is supporting have come close to complying with their commitments," Kerry told the House foreign affairs committee.
Kerry told lawmakers, "In Luhansk, and Donetsk, and now in Debaltseve, he (Putin) has empowered, encouraged, and facilitated directly land grabs in order to try to destabilize Ukraine itself."
And he renewed warnings that "if failure continues, there will be further consequences -- consequences that would place added strains on Russia's weakened economy."
"We are poised yet to do another round potentially, depending on what happens with (the cease-fire) in these next few days," Kerry said.
French Foreign Minister Laurent Fabius also said on February 25 that Moscow would face more European Union sanctions if the separatists attack the Kyiv-controlled strategic port of Mariupol.
Top U.S. officials have lashed out at Putin and his ministers in recent days as the fighting has continued in Ukraine, with Kerry on Tuesday directly accusing Russian leaders of lying "to my face" over the conflict.
Asked if she believed Putin's assertions that he wanted peace in Ukraine, National Security Advisor Susan Rice retorted: "How dumb do I look?"
"No. In all seriousness, no. One cannot accept Vladimir Putin at his word because his actions have belied his words repeatedly, particularly in the context of Ukraine," Rice told PBS television.
On the ground in eastern Ukraine, the first day without fatalities was reported since the cease-fire came into effect on February 15.
"Over the past day, one soldier was wounded but there were no dead," Ukrainian military spokesman Andriy Lysenko told journalists in Kiev. The rebels also reported no deaths on their side.
But the OSCE mission to Ukraine said it could still not confirm a pull-back of heavy weapons from the frontline.
Rebels have claimed they were withdrawing artillery, rocket launchers and tanks from some areas, and journalists saw a column of howitzer guns being driven along a road near the separatist stronghold of Donetsk.
OSCE monitors said the warring sides had not provided the information needed to determine what, if any, arms withdrawals have occurred.
Putin's spokesman, Dmitry Peskov, in an interview with CNN on February 25, accused OSCE monitors of "refusing" to observe the withdrawal of heavy weaponry by rebels in the Donetsk region.
But the head of the OSCE Parliamentary Assembly, Ilkka Kanerva said the separatists continued to impose restrictions on the monitors' movements.
Kanerva said in a statement that he was "profoundly disturbed" by the rebels' "continuing refusal to grant unlimited, safe access to OSCE monitors on the ground in Ukraine and their violations of the Minsk Package of Measures."
Ukraine has warned that it will not carry out an arms pull-back until a full and "comprehensive" cease-fire is observed and has accused Russia of continuing to send military hardware in to bolster the rebels.
Meanwhile, top U.S. defense leaders told Congress that the Obama administration is still debating whether to provide lethal defensive arms to Ukraine.
They expressed concern that such aid would only escalate Russia's military campaign there.
U.S. General Philip Breedlove, the top NATO commander, told the House Armed Services Committee that he has laid out military options the administration could consider for Ukraine, ranging from sending small arms to more sophisticated weapons that would take longer to arrive and require extensive training.
Breedlove and Christine Wormuth, defense undersecretary for policy, told lawmakers they are worried most that Russia might move on to destabilize non-NATO countries such as Montenegro or Moldova and expand its military assault into other portions of Ukraine.
In a sign of the damage the war has inflicted on Ukraine's economy, the central bank on February 25 imposed a temporary ban on purchases of foreign currencies, in an attempt to prop up the troubled hryvnya currency, which has lost some 70 percent of its value in the past year.
The ban should have been in effect from February 25 to February 27, but was reversed later in the day after criticism from Prime Minister Arseniy Yatsenyuk.
With reporting by Reuters, AFP, AP, dpa, and BBC