Secretary of State Rex Tillerson is meeting Russian President Vladimir Putin during his trip to Moscow, despite the Kremlin's statement following the U.S. airstrike against the Syrian regime that a meeting was not on the calendar.

A State Department spokesman confirmed the meeting.

That's a change from Monday, when Putin's spokesman said that "there is no meeting with Tillerson in the president's diary." The announcement was regarded as a pointed snub from Putin in response to President Trump's decision to authorize an airstrike in retaliation for Syrian President Bashar Assad's use of chemical weapons. The State Department demurred when asked for confirmation of the meeting.

The reversal suggests that Putin couldn't pass up the chance to assess Tillerson and the Trump administration's foreign policy in the secretary of state's first visit to Moscow, which is taking place in a more charged atmosphere than the Russians would have hoped. "We consider it crucially important to prevent a repetition of [attacks on Assad] in the future," Russian Foreign Minister Sergey Lavrov told Tillerson during their meeting earlier on Wednesday.

Tillerson had a noncommittal and modest opening reply, saying he hoped "to further clarify areas of sharp difference, so we can better understand why these differences exist and what the prospects for narrowing those differences may be."

Syria offers the opportunity for the most dramatic clash, where officials in both governments had seen previous opportunities for cooperation against ISIS. But Trump administration officials have mocked and condemned Russia for allowing the Assad regime to carry out the gas attack, whereas Russia has retorted that western powers might have staged the use of chemical weapons.

"We have information that a similar provocation is being prepared ... in other parts of Syria including in the southern Damascus suburbs where they are planning to again plant some substance and accuse the Syrian authorities of using [chemical weapons]," Putin said Tuesday.

State Department officials brushed off that accusation and reiterated that the use of chemical weapons is a "red line" for the United States. "It was crystal clear to us that this was carried out and it was carried out by the Syrian regime," acting State Department spokesman Mark Toner said.