Romanian Prime Minister Nicolae Ciuca has pledged to strengthen his country's deterrence and defense posture on the eastern flank of the North Atlantic Treaty Organization, saying the country stands on the "front line" of the war in Ukraine.

In a written interview with Kyodo News, Ciuca thanked Japan for a total of $200 million in emergency humanitarian aid for displaced people in Ukraine as well as Romania, Moldova, Poland, Hungary, Slovakia and the Czech Republic following "Russia's brutal, unjustified and unlawful invasion of Ukraine."

Romanian Prime Minister Nicolae Ciuca. (Photo courtesy of Government of Romania)(Kyodo)

Ciuca hailed NATO's recent decision to deploy four new combat units in Romania, Bulgaria, Hungary and Slovakia as part of efforts to bolster security on the eastern border of the trans-Atlantic alliance.

"We are an ally situated on the front line of this crisis," he said. "Romania is deeply concerned about the continuous Russian military aggression against Ukraine, with severe consequences for regional, European and international security."

Russian President Vladimir Putin has sent troops into Ukraine in what he calls a "special military operation" to demilitarize and "denazify" the country, a claim dismissed by the United States and other Western countries as a pretext for waging war.

After failing to take the capital Kyiv and other major Ukrainian cities, Russia has shifted its forces to a battle focused on southern and eastern parts of Ukraine, including the key port city of Mariupol.

Ciuca expressed hope that he, U.S. President Joe Biden and other NATO leaders will shape a "coherent, efficient and well-balanced" deterrence and defense posture on the eastern flank for the long term when they gather for a summit in Madrid in June.

He condemned Russian attacks on nuclear power facilities in Ukraine and Putin's earlier announcement that he was placing his nuclear forces into "special combat readiness."

"Russia must understand that threats to use nonconventional weapons will not yield any positive result," Ciuca said. "To the contrary, its international position will be further diminished, and the international community will continue to condemn such threats, no matter the disinformation spun by the Kremlin and the Russian state media."

"No propaganda can justify such threats or their materialization," he said.

Since Russia launched its invasion on Feb. 24, more than 640,000 Ukrainians, including many children, have entered Romania, and the government and local people have provided food, shelter and social services such as access to education, according to the prime minister.

"We have been monitoring the situation very carefully and have taken several measures to manage the massive inflow of people, in coordination with our neighbors and partners," he said. "We are facilitating the entry of all Ukrainian citizens that need protection."

Ciuca said most of the Ukrainians who entered Romania did not apply for asylum in the country because they were in transit to other European states where they have relatives.

"The numbers are fluctuating daily and it is difficult to estimate, at this point, how future inflows will look like," he said.