Tillerson's visit to Ukraine followed a first face-to-face meeting between President Donald Trump and Russia's Vladimir Putin on Friday at the G20 summit in Hamburg, Germany.
In that role, Volker will lead US efforts to implement the 2015 Minsk agreement aimed at halting the fighting in Ukraine's eastern Donbass region.
Tillerson said sanctions against Russian Federation would remain in place "until Moscow reverses its actions", including the return of the annexed Crimean peninsula.
Poroshenko thanked Tillerson for the continued US commitment to Ukraine's sovereignty and territorial integrity.
Ukraine's eastern regions of Donetsk and Lugansk have witnessed deadly clashes between pro-Russia forces and the Ukrainian army since Kiev launched military operations in April 2014 to crush pro-Moscow protests there.
A few days ago, Mr. Tillerson announced he was appointing a new special envoy, Kurt Volker, an experienced diplomat, to help settle the dispute in Ukraine in part at the request of Mr. Putin.
Kerber fights to round four
The third-round match was suspended Friday by darkness after 2 hours, 54 minutes with Querrey leading 6-5 in the fifth set. They returned to finish the contest on Saturday but it was all over in a matter of minutes as the 24th seed broke serve.
Exclusive Photos: The Progression Of The Friday Morning Fire In Oakland
She said she turned around and drove back to her neighborhood and found flames shooting from the building. It stretches across three blocks and had a planned 225 apartments and 2,300 square feet of retail space.
Destiny 2 Open Beta Gets Teaser Trailer
Destiny 2's social hub, The Farm , will make a brief appearance during the beta starting on Sunday, July 23 at 10 a.m. Destiny 2's beta will run from the 21st of July up until the 23rd and can only be accessed by pre-ordering the game.
Kiev and its European allies have been alarmed by Mr Trump's determination to improve relations with the Kremlin, despite its role in Ukraine and alleged meddling in last year's U.S. presidential election campaign.
Volker will "coordinate all State Department efforts to bring a resolution to the conflict created when Russian Federation invaded Crimea and later eastern Ukraine", Tillerson spokesman R.C. Hammond told Bloomberg.
Tillerson said sanctions will remain in place against Russian Federation "until Moscow reverses their actions". "And so I think that was about the way we expected the conversation to go". "We want to acknowledge that, (but) we still have more to do", he said.
He called the initial dialogue an effort to "explore a framework under which we might begin to have agreement on how to deal with these very complex issues of cyberthreats, cybersecurity, cyberintrusions".
He added, "I think the point was made that this was an issue that really has the American people quite concerned and again it, too, stands as an obstacle to our ability to improve our relationship between the United States and Russian Federation, and it needs to be addressed in terms of how we assure the American people that interference in our elections will not occur by Russian Federation or anyone else".
"The election interference really shows how complicated the use of these types of tools are becoming", Mr. Tillerson continued.