LONDON — Russia has warned of a "real war" with the US if the US attempts to issue it with an ultimatum over its support for Syrian President Bashar Assad.
British Foreign Secretary Boris Johnson will on Monday call for Western powers to impose sanctions on Russia if it fails to cut ties with Assad following last week's chemical attack on Syrian civilians.
Russia's embassy in London warned of a "real war" if the US and its allies imposed any such ultimatum.
Any such threat by the G-7 nations "brings us to real war," the embassy warned, before questioning the leadership of US Secretary of State Rex Tillerson and Johnson.
In a joint statement, Russian, Iranian, and Assad-supporting forces said the US attack on a Syrian air base last week had crossed a "red line" and warned that any further attacks would be responded to with force.
"What America waged in an aggression on Syria is a crossing of red lines," the statement said.
"From now on we will respond with force to any aggressor or any breach of red lines from whoever it is and America knows our ability to respond well."
If G7 ultimatum to Russia brings us to real war,what is your trust in @realDonaldTrump as a wartime leader&@BorisJohnson as his lieutenant?
— Russian Embassy, UK (@RussianEmbassy) April 9, 2017
Johnson was due to begin a visit to Moscow on Monday, but the foreign secretary cancelled the trip following a telephone conversation with Tillerson.
The decision led to condemnation and mockery both at home and abroad.
The Russian foreign ministry said Johnson had shown a "fundamental misunderstanding or lack of knowledge of the events in Syria, Russia's efforts to settle that crisis, and the general objectives of diplomacy."
"The decision to call off Johnson's visit to Moscow," it added, "confirms once again doubts in the presence of added value in speaking to the UK, which does not have its own position on the majority of present-day issues, nor does it have real influence on the course of international affairs, as it remains 'in the shadow' of its strategic partners. We do not feel that we need dialogue with London any more than it does."
Labour Shadow Chancellor John McDonnell insisted on Sunday that Johnson should have gone ahead with the visit, while Liberal Democrat leader Tim Farron said he had been left looking like a "poodle" of the US.
Former Scottish First Minister Alex Salmond said the decision had left Johnson looking "daft."
"The idea the foreign secretary can't be trusted because he might pursue his own line or have an independent thought or crossover what the Americans are going to say just makes him look like some sort of Mini-Me to the United States of America," he told 'The Andrew Marr Show."
"That's not a position any foreign secretary would want to be in."
In a statement issued after a telephone conversation with Canadian Prime Minister Justin Trudeau, UK Prime Minister Theresa May said there needed to be a "political solution" to the Syrian crisis.
"They agreed on their support for the US action, which we believe was an appropriate response to the barbaric chemical-weapons attack launched by the Syrian regime," a representative said.
"And they discussed the importance of Russia using its influence to bring about a political settlement in Syria, and to work with the rest of the international community to ensure that the shocking events of the last week are never repeated.
"They noted that the foreign secretary is working closely with his Canadian counterpart as part of diplomatic efforts to line up G-7 and like-minded support for a clear international position on the way ahead, in support of the US secretary of state's visit to Moscow.
"And they agreed to continue this close cooperation as we build support for a political solution to end the conflict and bring lasting peace and stability to Syria."
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