Russian Deputy Prime Minister Dmitry Rogozin, who oversees defence, said Saturday that Ukraine was its own worst threat, after Kiev announced plans to boost its armed forces because of the conflict in east Ukraine.

Rogozin quoted Ukrainian Defence Minister Stepan Poltorak as telling parliament Friday that Kiev faced threats both from pro-Russian separatists in its east and also from the pro-Russian separatist region of Transdniestr on its southwestern border.

"Poltorak talks about a dual threat. But the main threat to their security is not to the west and not to the east. Let them seek it in themselves," Rogozin said.

He wrote on Twitter after the United States on Friday passed a bill allowing the provision of lethal military aid to Ukraine and lawmakers approved fresh economic sanctions against Russia.

Rogozin, known for his outspoken comments, also slammed the US reaction after Russia this week clinched a deal with India to build 10 nuclear reactors during a visit by President Vladimir Putin.

US State Department spokeswoman Jen Psaki on Friday said of the deal that "it shouldn't be business as usual" with Russia.

"They behave like nasty little children," Rogozin said. "They envy others' successes and are glad of others' failures and try to trip up others everywhere."