U.S. Secretary of State John Kerry on Wednesday accused Russian authorities of lying about Russia’s role in the Ukraine conflict. He criticized Russia’s alleged support of Ukrainian rebels after a ceasefire agreed upon by both sides appeared to fall apart.

"Russia has engaged in a rather remarkable period of the most overt and extensive propaganda exercise that I've seen since the very height of the Cold War," Kerry said before the Senate on Tuesday, Al Jazeera reported.

"And they have been persisting in their misrepresentations - lies - whatever you want to call them - about their activities there to my face, to the face of others, on many different occasions."

Kerry accused Russia of trying to distort and downplay its involvement in providing troops and equipment to Ukraine’s rebels. "Russia is engaged in a massive effort to sway nations, to appeal to them, reach out to them, and fundamentally, tragically, sort of reigniting a new kind of East-West zero sum game that we think is dangerous and unnecessary, frankly,” he said.

But, Russian President Vladimir Putin has repeatedly denied arming, or providing troops for, rebels in eastern Ukraine.

The fighting, which began last April, has killed over 5,600 and displaced over a million people, and Kerry has met with Russian and Ukrainian officials several times since then to arrange a resolution to the conflict.

Senators at the meeting called upon the U.S. to provide more military support for Ukraine’s embattled army. "It is time for some more serious defensive arms to the Ukrainians. I think that the Russians at this point have proven that they are immune to other forms of influence," Senator Chris Murphy, D-Conn., reportedly said.

However, Kerry refused to provide his opinion about arming Ukraine’s troops, saying such discussions were still tentative. “Until the president makes his decision, I'm going to keep my consultations personal and private with him," he said.

The Pentagon is set to deploy between five and 10 troops to Ukraine to provide combat medical training to local military forces, The Associated Press reported.

Foreign ministers from France, Germany, Russia and Ukraine met on Tuesday in another attempt to salvage a broken ceasefire agreement for eastern Ukraine, agreed upon earlier in February.

Pro-Russian separatists on Tuesday showed reporters that they were complying with the accord by withdrawing heavy weapons from the area, Reuters reported. Rebel leaders also told reporters they would not make any further military advances.

"That's it. We are going no further," rebel commander Eduard Basuring reportedly said.

However, the Ukrainian military condemned the move as “empty words,” and claimed that the rebels were using a show of good faith to build up their forces for another strike.

Meanwhile, a report from Amnesty International said that illegal weapons like cluster bombs have been used during the conflict, AP reported.

"Taking into account everything we understand for now, we think that they were used by both sides," Anna Neistat, the organization's senior director for research, told reporters in Moscow on Wednesday.