In a stormy day at the United Nations, Russia's Ambassador to the UN accused Britain of supporting terrorist organisations, and directly linked their alleged support to the attacks on Coptic Christian churches earlier in the week.
Vladimir Safronkov, Moscow's envoy to the United Nations, accused Britain of supporting organisations who have been "murdering Christians and other minorities" in the Middle East, including attacking churches on Palm Sunday, a direct reference to the deadly bombings in Egypt over the weekend claimed by Daesh, killing some 21 people as they gathered to observe Christian religious rites.
The Russian diplomat's comments come following increasing tensions between Moscow and the West, after US President Donald Trump authorised a limited military strike last Friday ostensibly to punish Syrian dictator Bashar Al-Assad for using chemical weapons in a sarin gas attack on civilians in Khan Sheikhoun, Idlib.
The Assad regime is sponsored by the Kremlin who, in a joint alliance with Iran and its proxy Shia jihadist militias, has been propping up the beleaguered Syrian despot since 2011 before intervening militarily to shore up his regime in late 2015.
Clearly and visibly angered by the US strike on the regime airbase at Shayrat near Homs in west-central Syria, Safronkov even took aim at UK ambassador to the UN Matthew Rycroft, ordering her to "look at me when I'm speaking to you".
US-Russia ties 'deteriorated' under Trump
The tense day at the UN comes as US Secretary of State Rex Tillerson holds talks with senior Russian officials, including President Vladimir Putin. Washington's top diplomat was reportedly received icily by his Russian counterparts.
Putin said on Wednesday trust had eroded between the United States and Russia under President Donald Trump, as Moscow delivered an unusually hostile reception to Tillerson in a face-off over Syria.
Tillerson started a meeting with Putin in the Kremlin after talking to his Russian opposite number Sergei Lavrov for around three hours. The Kremlin had previously declined to confirm Putin would meet Tillerson, reflecting tensions over the US strike on Syria.
Just as Tillerson sat down for talks with Lavrov earlier on Wednesday, a senior Russian official assailed the "primitiveness and loutishness" of US rhetoric, part of a volley of statements that appeared timed to maximise the awkwardness during the first visit by a member of Trump's cabinet.
Putin told Russian television:
One could say that the level of trust on a working level, especially on the military level, has not improved but has rather deteriorated.
In his interview, Putin doubled down on Russia's support for the Assad regime, repeating denials that Al-Assad's government was to blame for the sarin attack last week and adding a new theory that the attack may have been faked by Al-Assad's enemies.
Tillerson's official itinerary in Moscow started with the meeting with Lavrov, in an ornate hall in a foreign ministry-owned residence. In opening remarks in front of reporters, Lavrov greeted Tillerson with unusually icy remarks, denouncing the missile strike on Syria as illegal and accusing Washington of behaving unpredictably.
"I won't hide the fact that we have a lot of questions, taking into account the extremely ambiguous and sometimes contradictory ideas which have been expressed in Washington across the whole spectrum of bilateral and multilateral affairs," Lavrov said.
"And of course, that's not to mention that apart from the statements, we observed very recently the extremely worrying actions, when an illegal attack against Syria was undertaken."
Lavrov also noted that many key State Department posts remain vacant since the new administration took office – a point of sensitivity in Washington.
One of Lavrov's deputies was even more undiplomatic. Deputy Foreign Minister Sergei Ryabkov told Russia's state-owned RIA news agency that:
In general, primitiveness and loutishness are very characteristic of the current rhetoric coming out of Washington. We'll hope that this doesn't become the substance of American policy.
"As a whole, the administration's stance with regards to Syria remains a mystery. Inconsistency is what comes to mind first of all."
Tillerson kept to more calibrated remarks, saying his aim was "to further clarify areas of sharp difference so that we can better understand why these differences exist and what the prospects for narrowing those differences may be."
"I look forward to a very open, candid, frank exchange so that we can better define the US-Russian relationship from this point forward," he told Lavrov.
After journalists were ushered out of the room, Lavrov's spokeswoman, Maria Zakharova, wrote on her Facebook page that US journalists travelling with Tillerson had behaved as if they were in a "bazaar" by shouting questions to Lavrov.
Moscow's hostility to Trump administration figures is a sharp change from last year, when Putin hailed Trump as a strong figure and Russian state television was consistently full of effusive praise for him.
Assad's WMD cover-up
The White House has accused Moscow of trying to cover up Assad's use of chemical weapons after the attack on a town killed 87 people last week.
Trump responded to the gas attack by firing 59 cruise missiles at a Syrian air base on Friday. Washington warned Moscow, and Russian troops at the base were not hit.
Moscow has stood by Assad, saying the poison gas belonged to rebels, an explanation Washington dismisses as beyond credible. Putin said that either gas belonging to the rebels was released when it was hit by a Syrian strike on a rebel arms dump, or the rebels faked the incident to discredit Al-Assad.
Trump came to the presidency promising to seek closer ties with Russia and greater cooperation fighting against their common enemy in Syria, Daesh. Tillerson is a former oil executive who was awarded Russia's Order of Friendship by Putin.
Last week's poison gas attack and the US retaliation upended what many in Moscow hoped would be a transformation in relations between the two countries, which reached a post-Cold War low under Trump's predecessor Barack Obama.
Russia, meanwhile, intervened in the civil war on Assad's side in 2015 and has troops on the ground, which it says are advising government forces. Both Washington and Moscow say their main enemy is Daesh, although they back opposing sides in the wider civil war which has killed more than 400,000 people and spawned the world's worst refugee crisis.
In an interview with the Fox Business Network, Trump said he was not planning to order US forces into Syria, but that he had to respond to the images of dead children poisoned in the gas attack.
"We're not going into Syria," he said in excerpts of the interview on the station's website.
But when I see people using horrible, horrible chemical weapons…and see these beautiful kids that are dead in their father's arms, or you see kids gasping for life…when you see that, I immediately called [Defense Secretary] General Mattis.
Tillerson travelled to Moscow with a joint message from Western powers that Russia should withdraw its support for Al-Assad after a meeting of the Group of Seven (G7) industrialised economies also attended by Middle East allies.
Tillerson's mission sees the Trump administration taking on the traditional US role as spokesman for a unified Western position.
Trump's relations with Russia are also a domestic issue, as US intelligence agencies have accused Moscow of using computer hacking to intervene in the election to help Trump win. The FBI is investigating whether any Trump campaign figures colluded with Moscow, which the White House denies.