The US President claimed his negotiating tactics were helping build peaceful relations with hostile foreign powers like North Korea.
Mr Putin and Mr Trump will meet at a summit in Helsinki on Monday, with thousands of human rights’ protestors marching in the Finland capital on Sunday.
The White House chief even admitted he got along with brutal North Korean dictator Kim Jong-Un, who he has previously threatened with “fire and fury”.
Mr Trump said: “I’d like to see peace. A lot of people thought I’d be, most people said, “On day one we’re going to be at war with Trump as President.
“Well, here it is – we’re getting rid of wars. We’re getting out of wars.”
He added that he got along “great” with Kim Jong-Un, calling him “very smart, great personality, funny and tough, good negotiator.”
Mr Trump said: “Sure he’s ruthless. Plenty of people I deal with are pretty ruthless people.”
Monday’s talks with Mr Putin come after 12 Russians were indicted in the US over alleged hacking of Democratic officials in the 2016 US election.
The UK government has accused Moscow of being behind the Salisbury Novichok nerve attack on Sergei Skripal and his daughter Yulia.
British citizens Dawn Sturgess and Charlie Rowley are thought to have become victims of the same batch of the nerve agent, with police launching a murder investigation when Ms Sturgess died.
Mr Trump said Putin was “probably” ruthless, but has not said if he will press the Russian leader over the Salisbury and Amesbury attacks.
The US President again criticised UK over immigration, saying it made him “very sad”.
He said: “I said Brexit was going to happen for a specific reason: immigration.
“I think the people of the UK want to have who they want to have in their country, and I think that what’s happening is very sad.
“On a humanitarian basis, you’ve got to do something, and yet it’s changing Europe. You take a look at what’s happened in London and Paris.
“It’s changing Europe and I don’t mean in a positive way.”