JUDY WOODRUFF: New tensions between the United States and Russia dominated this day. America's top diplomat carried U.S. grievances over Syria and other issues to Moscow, while President Trump spoke out in Washington.
Our chief foreign affairs correspondent, Margaret Warner, has our report.
MARGARET WARNER: The discord was on display at the very outset of Secretary of State Rex Tillerson's meetings with Russian Foreign Minister Sergei Lavrov.
SERGEI LAVROV, Russian Foreign Minister (through interpreter): We have a lot of questions regarding very ambiguous and as well as sometimes contradictory ideas on coming from Washington.
MARGARET WARNER: Tillerson acknowledged sharp differences, and after meeting privately with Russian President Vladimir Putin, he emerged with an even grimmer appraisal.
REX TILLERSON, U.S. Secretary of State: The current state of U.S.-Russia relations is at a low point. There is a low level of trust between our two countries. The world's two foremost nuclear powers cannot have this kind of relationship.
MARGARET WARNER: The most immediate trigger for tensions, a deadly sarin gas attack in Syria last week, and the U.S. response, a cruise missile strike on a Syrian air base. Lavrov again denied Russia's ally the Syrian government was responsible.
SERGEI LAVROV (through interpreter): We believe it's necessary to have an international, unbiased, frank investigation into this incident. There were no signs that would support the statement, the allegation that chemical agents were used there at all.
MARGARET WARNER: Tillerson insisted again that Syria's government did carry out the attack, and he called again for Russia to abandon President Bashar al-Assad.
REX TILLERSON: We do think it's important that Assad's departure is done in an orderly way, an orderly way, so that certain interests and constituencies that he represents feel that they have been represented at the negotiating table for a political solution. How that occurs, we leave that to the process going forward.
MARGARET WARNER: But in New York this afternoon:
NIKKI HALEY, U.S. Ambassador to the United Nations: It is long past time for Russia to stop covering for Assad.
MARGARET WARNER: Russia vetoed a U.N. Security Council resolution condemning the gas attack in Syria.
The chill in Moscow today was a far cry from the atmosphere a year ago. Then-candidate Donald Trump repeatedly praised Vladimir Putin during the campaign, and he suggested a rapprochement with Russia was both desirable and possible. That all changed with last week's gas attack and President Trump's quick response.
Even before the meetings, President Putin gave his own pointed assessment of U.S.-Russia relations today on Russian state television.
VLADIMIR PUTIN, Russian President (through interpreter): It is possible to say that the level of trust on a working level, especially on the military level, it has not improved, but rather has deteriorated.
MARGARET WARNER: In turn, President Trump had harsh new words for the Russians and their Syrian ally Assad in an interview that aired on FOX Business Network.
PRESIDENT DONALD TRUMP: If Russia didn't go in and back this animal, you wouldn't have a problem right now. Frankly, Putin is backing a person that's truly an evil person. And I think it's very bad for Russia. I think it's very bad for mankind. It's very bad for this world.
MARGARET WARNER: Mr. Trump followed up at a joint White House news conference with NATO's secretary-general.
PRESIDENT DONALD TRUMP: Right now, we're not getting along with Russia at all. We may be an all-time low in terms of relationship with Russia. This has built for a long period of time, but we are going to see what happens.
MARGARET WARNER: Tensions are over more than Syria. In Moscow, Secretary Tillerson again criticized Russia's intervention in Ukraine, which triggered Western sanctions.
REX TILLERSON: Until full progress is made under the Minsk accords, the situation in Ukraine will remain an obstacle to improvement in relations between the U.S. and Russia.
MARGARET WARNER: Lavrov gave no ground on Ukraine or charges of Russian meddling in the U.S. election. The two men did agree to establish a working group to try to stabilize relations.
For the PBS NewsHour, I'm Margaret Warner.