The United States is unlikely to serve as an effective mediator in international conflicts, given its actions on the global stage, senior Russian security official Dmitry Medvedev said on Thursday.

The comments by Medvedev, a former president of Russia, appeared to contrast with the Kremlin's official line that the U.S. is playing a valuable role in seeking a peace settlement between Russia and Ukraine.

"It is hardly possible to consider that a country which kidnaps presidents and starts conflicts just like that can act as an effective mediator in all situations," Medvedev told an audience at an educational forum.

He appeared to be referring to the Iran war and also to the U.S. special forces' operation ordered by President Donald Trump in January to capture Venezuelan President Nicolas Maduro and bring him to the U.S. to face trial on drug charges.

However, Medvedev did acknowledge that Trump's administration was making an effort to resolve the Ukraine conflict - in contrast, he said, with the previous president, Joe Biden.

Medvedev, deputy chairman of Russia's Security Council, is one of the country's most hawkish officials and frequently makes acerbic comments on global affairs.

In the same talk on Thursday, he said that Europe was undergoing a process of militarisation that he compared to the build-up to World War Two.

Medvedev also said that 450,000 people had signed contracts to join the Russian armed forces in 2025, and a further 127,000 so far this year.

Following an unpopular compulsory mobilisation in 2022, Moscow now relies on recruiting professional soldiers to wage the war in Ukraine, now in its fifth year, and offers them generous payments for signing up.

Neither Russia nor Ukraine publicly reveals casualty numbers. Russian news outlet Mediazona says it has confirmed at least 213,858 Russian military deaths as of last week, in a joint investigative project with the BBC Russian service.

-Lucy Papachristou/Reuters