US and British senior diplomats will discuss easing restrictions on Ukraine's use of Western weapons amid its war with Russia during their visit to Kiev that began Wednesday. 

The joint trip is composed of US Secretary of State Antony Blinken and UK Foreign Secretary David Lammy, whose newly-appointed government has pledged to be Ukraine's key defender.

The visit coincides with Ukrainian President Volodymyr Zelensky's pressure on his Western allies to provide more power weapons with fewer restrictions.

"We're working that out right now," US President Joe Biden said, concerning Kiev's use of longer-range weapons.

Despite Biden being one of Ukraine's strong supporters, he previously stated he wants to prevent direct conflict between the United States and Russia, the world's two major nuclear superpowers, though he has been consistently escalating the war by giving stronger weapons to Ukraine, with US forces also assisting Ukraine with intelligence in strikes on Russia.

Washington is committed to providing Kiev with "what they need when they need it to be most effective in dealing with the Russian aggression," Blinken said in London on Tuesday alongside Lammy.

However, the secretary of state, who is on his fifth visit to Kiev since the start of its ongoing war, highlighted the importance of seeing if Ukrainian forces are able to maintain and operate certain weapons.

"We never rule out, but when we rule in, we want to make sure it's done in such a way that it can advance what the Ukrainians are trying to achieve," Blinken told Sky News about the US allowing Ukraine to use long-range weapons.

Strikes on Russia possibly already decided

Western nations may have already decided to strike Russia using US-made ATACMS missiles, the Kremlin said on Wednesday, noting that recent media reports are part of an effort to formalize this decision.

"It is possible that the decision to strike Russia with ATACMS missiles has already been made, and the West is trying to formalize it through media reports," Kremlin spokesperson Dmitry Peskov told reporters.

Peskov's remarks follow a Tuesday report from The Times, which cited sources indicating that the United States might lift its ban on Kiev striking deep into Russian territory within weeks.

According to the report, some members of the US administration have shifted their stance and are working to convince the rest of the White House staff and President Joe Biden to support the change.

In a related development, Axios journalist Juliegrace Brufke reported, citing a senior US official, that Blinken is expected to grant Ukraine permission to use US-made ATACMS missiles against Russia during his visit to Kiev.

"Most likely, all these decisions have already been made; this can be assumed with a high degree of probability," Peskov added. "At the moment, such an information campaign is simply being conducted in the media to formalize the decision that has already been made."

"At the same time, attempts are continuing to distance themselves from involvement in this conflict on the part of the United States and European countries. We do not think that this is working out," he underlined.

The deployment of Army Tactical Missile System (ATACMS) missiles to Ukraine has been a point of contention, with reports from April suggesting that the US had given Kiev the system covertly. The missiles have a range of up to 300 kilometers (approximately 186 miles), which would significantly enhance Ukraine's ability to strike targets deep within Russian territory.

US cannot be trusted over long-range weapon ban on Ukraine: Russia

Washington's claims of banning Ukraine from using US-supplied long-range weapons for deep strikes into Russian territory cannot be trusted, Moscow's ambassador to the US Anatoly Antonov said last month.

Ukrainian President Volodymyr Zelensky resumed calls with the US to allow Kiev's troops to use long-range weapons during its ongoing incursion in the Kursk Region.

However, the Pentagon reiterated its stance of preventing the former Soviet nation from using the US-supplied ATACMS missiles, which have a range of up to 300km, for strikes inside Russian territory.

US officials “seem to be constantly teasing us by saying that today it is allegedly not allowed to use long-range systems to strike at Russian territory," Antonov told journalists on Friday, adding that "in reality, they are essentially preparing the ground to simply remove all existing restrictions, at a certain point."

The Russian envoy based his judgment on the US' previous support of Kiev during its war with Moscow, expressing his certainty to TASS that Ukraine will “fight with US-made [long-range] weapons against us,” adding, “Where exactly will it happen? We cannot say or foretell."