(Source: CGTN)

Russia vetoed a United Nations Security Council resolution condemning last week's alleged use of chemical weapons in Syria and calling for an investigation. The attack prompted US missile strikes on a Syrian air base, widening the gap between Washington and Moscow... a gap that was laid bare once again at UN headquarters.

Staffan de Mistura holds regular monthly briefings at the UN Security Council on the situation in Syria. But after last week's alleged chemical weapons attack and the US airstrike in response this one was more highly charged than most.

"Let us view this moment of crisis -- and it is a moment of crisis -- as a watershed and an opportunity perhaps for a new level of seriousness in the search for a political solution," Mr De Mistura said.

Mr De Mistura urged the US and Russia to work together, saying a political solution was the only way forward in Syria and even as he was speaking, US Secretary of State Rex Tillerson was meeting his counterpart Sergei Lavrov in Moscow. But those talks weren't enough to prevent yet another display of gridlock at the Security Council later, in a vote on a resolution condemning the alleged chemical weapons attack.

Russia said the document pre-judged who was responsible for the suspected gas attack, since despite denials from Damascus, Western powers have already said the Assad government is most likely behind it.

"The main problem was that the draft resolution by the troika appointed the guilty party prior to an independent and objective investigation. This is an approach that is incompatible with legal norms," said Vladimir Safronkov, deputy Russian ambassador to the UN.

But the US said Moscow's continual backing for the Syrian government would only make it more isolated.

"To Assad and the Syrian government. You have no friends in the world after your horrible actions. The United States is watching your actions very closely. The day of your arrogance and disregard for humanity are over," said Nikki Haley, US ambassador to the UN.

UN diplomats say Russia's put forward a rival resolution condemning the gas attack and the US strike, though it's not clear if that will come to a vote. In the meantime, Staffan de Mistura is pinning hopes on a sixth round of peace talks, starting in Geneva in May.