Ukraine Prime Minister Arseniy Yatsenyuk, 40, confirmed Russian military forces and equipment have entered Ukraine, state-run media reported Monday. "I have just spoken with the national defense and security council secretary,” Yatsenyuk said. “Ukrainian military intelligence confirm the fact military personnel and equipment have been transferred from Russia to Ukraine.”

Yatsenyuk detailed the weapons and other military equipment and vehicles that entered the eastern European country -- the largest country located entirely in Europe, CNN reported.

"Tanks, GRAD multiple rocket systems, BUK and SMERCH systems, radio electronic intelligence systems are not sold at local Donetsk street markets. Only the Russian army and Defense Ministry have them,” Yatsenyuk said.

Russian officials could not be reached for comment, CNN said.

The news from Ukraine came only one day after a number of protestors marched for peace in Kiev’s Independence Square. Yatsenyuk and Ukraine President Petro Poroshenko attended the protest where participants shouted “I am Volnovakha” in tribute to 13 passengers who died near the city of Volnovakha after their bus was hit by artillery fire Jan. 13.

"We will remember every Ukrainian hero who gave [his life] for the sake of independence, sovereignty and territorial integrity of Ukraine," Poroshenko said. "We will not give up a single meter of our land."

Meanwhile, pro-Russian separatists renewed attacks on Ukrainian military at an airport on Monday after Kiev launched a major plan to reclaim lost ground that Russia deemed a "strategic mistake." The attack left three dead and 66 wounded.

In March 2014, Russia annexed the Crimean Peninsula in defiance of western opposition and has been supporting the Ukrainian separatists seeking independence -- or at least autonomy -- from Kiev. 

In December, data from the Stockholm International Peace Research Institute confirmed Russia had begun investing in upgrading its military forces, purchasing weapons and military equipment. Russian defense companies increased sales by more than 20 percent from the last year. Russian president Vladimir Putin also said he planned to spend more than 20 trillion rubles, or $700 billion by 2025.