UNITED NATIONS -- Russia vetoed a U.S. resolution that would extend the mandate of chemical weapons inspectors in Syria on Thursday.

"Russia has killed the Joint Investigative Mechanism," U.S. Ambassador Nikki Haley told the United Nations Security Council after the vote.

The U.N. failed to extend the mandate of the inspectors, who had been given a joint mandate by the Organization for the Prohibition of Chemical Weapons (OPCW) and the U.N. to assign blame for chemical attacks against civilians.

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"Russia has entered the realm of double digits with its tenth veto on Syria since 2011, sending another shameful message that they will protect the Syrian government at the cost of the Syrian people ... U.N. member states should insist on continued investigations into chemical attacks so perpetrators can be held to account," said Louis Charbonneau, U.N. director at Human Rights Watch.

The U.S. and Russia circulated rival U.N. resolutions Thursday for a second time to extend the work of experts seeking to determine who is responsible for chemical weapons attacks in Syria.

After the meeting, Japan circulated a draft resolution, for a vote as soon as Friday, to extend the mandate of the Chemical Weapons inspectors of the "JIM" by one month, which would give the U.S. and Russia time to craft a possible compromise.

Last month, Russia vetoed a U.S.-sponsored Security Council resolution that would have renewed the mandate of the experts from the U.N. and the international chemical weapons watchdog for a year, a mandate that ends Thursday at midnight.

Two days after Russia's last veto, the Joint Investigative Mechanism (JIM) released a report blaming Syria's government for a sarin nerve gas attack last April on the town of Khan Sheikhoun that killed more than 90 people and the Islamic State of Iraq and Syria (ISIS) extremist group for a mustard gas attack at Um Hosh in Aleppo in September 2016.

The 33-page report says the "leadership panel is confident that the Syrian Arab Republic is responsible for the release of sarin at Khan Shaykhun."

The inspectors of the JIM, who were unable to visit Khan Shaykun, based their findings on "sufficient credible and reliable evidence" of Syrian aircraft that dropped munitions, the crater that was caused by the impact of the aerial bombing, interviews with victims, and their finding that sarin identified in the samples taken from Khan Shaykhun was most likely been made with a precursor (DF) from the original stockpile of the Syrian Arab Republic.

After the report was issued, the White House issued a statement blasting Syrian President Bashar Assad's regime.

"This unconscionable attack marks the fourth time that the JIM has confirmed that the Assad regime used chemical weapons, underscoring the brutal and horrifying barbarism of Bashar al-Assad and making the protection provided by Russia even more egregious."

A fact-finding mission by the chemical weapons watchdog, the OPCW, reported on June 30 that sarin nerve gas was used in the Khan Sheikhoun attack.

But the job of determining responsibility for chemical attacks was given to the JIM, initially in a joint U.S.-Russian resolution.

The new U.S. draft resolution voted on Thursday, which Haley said had been revised three times to accommodate Russia's requests, would reaffirm support to the OPCW fact-finding mission and the JIM.

Russia's U.N. Ambassador Vassily Nebenzia circulated a Russian draft also to be considered Thursday, but withdrew it at the council meeting. On Monday, anticipating a fight, Nebenzia said, "It is important that the JIM is renewed but on the updated mandate because systemic errors that we saw with the recent report should be corrected. And that is the aim of our draft resolution."

Nebenzia on Thursday said: "There is nothing balanced about the U.S. draft resolution ... none of the basic flaws were remedied. You bear the responsibility if the mechanism cannot be salvaged."

He later called the last report on Syria, "a joke, complete nonsense" -- but added that Moscow would like the inspectors' mandate renewed.

Ambassador Matthew Rycroft, the U.K.'s permanent representative to the U.N., ahead of the Security Council vote on Syria chemical weapons, said, "The Joint Investigative Mechanism has found conclusively that both the Assad regime and Daesh [ISIS] have used chemical weapons in Syria ... that work demonstrates why we need a Joint Investigative Mechanism that is beyond politics, that is scientific, that is professional and that is objective."

Earlier in the week, a U.S. spokesperson said, "Russia has refused to engage on our draft resolution -- which the vast majority of council members agree is the most viable text -- in spite of our multiple attempts to consider Russian concerns."

In retaliation for the sarin attack, the U.S. launched a cruise missile strike against a Syrian airfield where the chemical weapons were launched.

In an apparent reference to that strike, Haley said that the "Assad regime should be on clear notice ... it would be wise for the Assad regime to heed that warning."

"What a shame it is," Haley said.

The veto will prevent inspectors from doing their job and investigating chemical weapons attacks in Syria unless a new agreement is struck to extend them.

Speaking to reporters before the vote, Haley said, "We will fight for what we know is right, we'll fight for what is fair, at the end of the day this is about holding people accountable and protecting innocent lives."

Meanwhile, a Council diplomat leaving Thursday's meeting said that, after consulting the lawyers, "There is a growing consensus that the mandate ends at midnight Friday instead of Thursday, as we all thought," leaving hope of an 11th hour compromise.