U.S. President Donald Trump has said he shows firmness in his dealings with Russian President Vladimir Putin.

"I think I'm very tough with him personally. I had a meeting with him. The two of us. It was a very tough meeting and it was a very good meeting," Trump said in an interview with the CBS TV network.

Trump said he is much more actively supporting Ukraine to strengthen its armed forces than ex-President Barrack Obama.

"I'm the one that gave Ukraine offensive weapons and tank killers. Obama didn't. You know what he sent? He sent pillows and blankets. I'm the one - and he's the one that gave away a part of Ukraine where Russia now has this…" Trump said.