Trump congratulates Putin on his inauguration

US President Donald Trump has congratulated his Russian counterpart Vladimir Putin on being sworn in for a fourth term, saying he looks forward to a time when the two nations can have a good relationship.

"The president congratulates him and looks forward to a time when we can hopefully have a good relationship with Russia," White House Press Secretary Sarah Sanders told reporters at her daily news conference yesterday.

"However, the United States believes that everyone has a right to be heard and assemble peacefully," she said, referring to the arrest of protesters in Russia.

Nearly 1,600 protesters, including Putin's most vocal opponent, Alexei Navalny, were detained on Saturday during nationwide rallies against the Russian leader.

She reiterated that Democrats were using the Russia investigation as an excuse for losing the 2016 election.

"I think he thinks that the idea that this narrative continues to be driven. The fact that, a year-and-a-half later, after spending most all of your time, every single day, looking into this and still finding nothing, the fact that we're still talking about it and has the potential to impact the 2018 election," Sanders said.

"The point he's making is how ridiculous it is that we're still having this conversation and the depths to which this research has gone on and investigation has been conducted and still produced nothing," she added.