But even if there is a definitive finding of Russian complicity, it's not clear the Pentagon or the White House would make that information public, a senior United States official said. The Kremlin had previously declined to confirm Putin would meet Tillerson, reflecting tensions over the USA strike on Syria.
Russian Foreign Minister Sergei Lavrov said in Moscow following his talks with Tillerson that the OPCW should be allowed to carry out an "objective investigation".
"One could say that the level of trust on a working level, especially on the military level, has not improved but has rather deteriorated", Mr Putin said.
The two leaders were expected to discuss disagreement about whether Syrian President Bashar Assad or his opposition was responsible for a chemical weapons attack last week that led to USA retaliatory cruise missiles.
"Right now we're not getting along with Russian Federation at all", Trump said at a White House press conference with NATO Secretary-General Jens Stoltenberg.
Lavrov had greeted Tillerson with unusually icy remarks, denouncing the missile strike on Syria as illegal and accusing Washington of behaving unpredictably.
One of Mr Lavrov's deputies was even more scathing.
Trust between Russia and the U.S. has degraded under the Trump administration, Russian President Vladimir Putin stated. -Russian air safety agreement over Syria which Moscow suspended after the USA missile strikes.
The palpable tension hanging over Tillerson's trip spoke to a widening chasm between the two world powers.
"The world's two foremost nuclear powers can not have this type of relationship", Mr Tillerson warned.
Moscow's hostility to Trump administration figures is a sharp change from a year ago, when Putin hailed Trump as a strong figure and Russian state television was consistently full of effusive praise for him.
The Trump administration concluded that Assad was behind the act, and on Thursday ordered a cruise missile strike against a Syrian airbase as a "proportional response".
Iran election: President Rouhani registers to run again
During the previous presidential election in June 2013, Rouhani garnered 50.7 percent of a total of over 36 million votes. Rouhani has arrived at the Interior Ministry where candidates enroll, Trend correspondent reported April 14.
Lavrov, echoing past denials of any Russian hacking or other interference in the electoral process, said Moscow hasn't seen "a single fact, or even a hint at facts" proving the US allegations of Russian interference.
Moscow has insisted that the civilians who died there were killed by toxic agents released from a rebel chemical arsenal struck by Syrian warplanes. The decision not to meet civil society leaders is sadly consistent with the Trump administration's retreat from a long-standing practice of support for human rights and democracy activists overseas.
Earlier, Russia vetoed a draft resolution at the UN Security Council presented by the US, UK and France that would have condemned last week's chemical attack in Syria and demanded that Damascus cooperate with investigators.
China, which has vetoed six resolutions on Syria since the civil war began, abstained from Wednesday's United Nations vote, along with Ethiopia and Kazakhstan.
Trump indicated early on that human rights would have no role in his foreign policy, and in particular that rights would have no role in the USA relationship with Russian Federation.
The stark language is the most blunt terms Trump has used to describe the Syrian president who is accused of war crimes in an attempt to hold onto power during a prolonged civil war.
Western ambassadors blasted Russian Federation earlier Wednesday for continuing to support Syrian President Bashar al-Assad after his alleged use of sarin on a rebel-held area of his country.
As Russia did Wednesday, by vetoing a proposed UN Security Council investigation into the sarin attack - which Putin pretends was the victims' fault.
But the two nations remain at odds over US airstrikes on Syria - following last week's chemical attack on Syrian civilians. "It's very bad for this world".
"Frankly, Putin is backing a person that is truly an evil person", Trump said.
"We will keep monitoring the issue, since the only possible reason for using military force on the territory of Syria is to fight terrorism", Lavrov said.
Sergey Lavrov said that inspectors from the Organisation for the Prohibition of Chemical Weapons should both visit the Syrian air base, which the U.S. said served as a platform for the attack, and the town of Khan Sheikhoun that was hit to get a full and objective picture.