By Veronica Stracqualursi and Manu Raju, CNN

(CNN) -- Kentucky Republican Sen. Rand Paul announced Wednesday that he delivered a letter to Russian President Vladimir Putin from US President Donald Trump.

"I was honored to deliver a letter from President Trump to President Vladimir Putin's administration," Paul tweeted.

"The letter emphasized the importance of further engagement in various areas including countering terrorism, enhancing legislative dialogue and resuming cultural exchanges," Paul said.

CNN has reached out to Paul's office and the White House for more details.

Paul spoke with Trump multiple times ahead of the senator's travel to Moscow, both in person and in the Oval Office, according to a source with knowledge of the matter.

Paul, a member of the Senate Foreign Relations Committee, had planned this Russia trip before the Helsinki summit, the source said. After the summit, Paul and Trump discussed the senator's planned Russian meetings and the messages the president wanted Paul to convey to them.

Paul received the letter before leaving Washington and then hand-delivered it to the Russian government, the source said.

According to Russian state news agency RIA Novosti, Putin's press secretary Dmitry Peskov confirmed that the letter was sent to Putin "through diplomatic channels," but the Kremlin has not yet reviewed it.

Paul has been in Russia this week on a trip he sees as a continuation of Trump's diplomatic outreach to Putin.

On Monday, the Kentucky Republican invited Russian lawmakers to Washington "to continue dialogue on vital issues such as nuclear non-proliferation and combating terrorism," which comes several weeks after Trump invited Putin to DC as well.

Paul remained supportive of Trump following the US President's performance during a news conference with Putin in July. Trump said then that he doesn't "see any reason why" Russia would be responsible for the election hacking, accepting Putin's denial over the US intelligence community's assessment. Facing public pressure, including criticism from some Republicans, Trump later said he misspoke.

This story has been updated with additional developments.