Ukraine's army awaited orders to pull back weapons from the front Line Thursday as a shaky truce settled, while the United States and Russia traded blame for delays in the peace plan.

Kiev said that its positions around the conflict zone came under fire from pro-Russian rebels a relatively low seven times in 24 hours, and neither side reported any fatalities for the second day running.

Military spokesman Anatoliy Stelmakh said Ukrainian forces were now "waiting for a decision" to start the withdrawal of heavy weapons - the next key step of the EU-brokered truce deal.

Rebels insist they have already begun 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 Wednesday.

But there was still no confirmation from the Organization for Security and Cooperation in Europe (OSCE) of any pull-back, with its monitors saying the warring sides had not provided the information needed to determine what, if any, arms withdrawals have occurred.

While fighting subsided, tensions between the West and Moscow in the worst crisis since the end of the Cold War swirled on unabated.

Addressing U.S. lawmakers Wednesday, Secretary of State John Kerry said Russia and pro-Moscow rebels had failed to meet the terms of the cease-fire.

Russian President Vladimir Putin had put in place policies that "violate all the international norms with respect to territory and behavior," Kerry told U.S. lawmakers on a foreign affairs committee.

"He has empowered, encouraged, and facilitated directly land grabs in order to try to destabilize Ukraine itself."

"To date, neither Russia nor the forces it is supporting have come close to complying with their commitments," he said, renewing warnings that Moscow would face further sanctions.

Top U.S. officials have lashed out at Putin and his ministers in recent days, and both the U.S. and Europe have warned fresh sanctions against Russia could be on the table if the peace plan stalls.

But Moscow has called threats of new punishment against it evidence that the West is not interested in the success of the troubled truce aimed at stopping fighting that has cost at least 5,800 lives since April.

"Behind these calls lies the unwillingness of these figures, these relevant countries, the United States, the European Union, to seek the implementation of what was agreed," Russia's Foreign Minister Sergei Lavrov said.

Russia, meanwhile, has ratcheted up its own pressure over the past few days by warning it could cut off gas supplies to Ukraine - and, by extension, to parts of the European Union.

Putin said Wednesday that Ukraine had paid only enough for three or four more days of gas deliveries and that state-run Gazprom would "terminate the supply" if it didn't receive money fast.

The West says the best hope for a negotiated solution to the 10-month conflict lies with the truce, which last week won unanimous backing from the U.N. Security Council.

But breaches by rebel forces - especially their assault on Debaltseve, a strategic transport hub, and attacks on Ukrainian army positions near the port city of Mariupol - have exasperated the EU and U.S.

British Prime Minister David Cameron this week announced his country will send up to 75 soldiers to Ukraine on a "training mission." He said they would not be sent to the conflict zone.

Up to 2,000 Russian soldiers were, meanwhile, taking part in drills near the Russian border with Estonia and Latvia, in a show of strength likely to alarm the EU neighbors.

The drills, which were to see some 1,500 troops parachute en masse, were to continue until Saturday, Moscow's military told AFP.