Jeremy Corbyn and his Shadow Defence Secretary Nia Griffith have "briefly" spoken after a row broke out in Labour ranks over Nato's role in eastern Europe, IBTimes UK has learned.
A source close to the Labour leader said the MPs both agreed "there needs to be a de-escalation of tension in the region".
A separate source close to Griffith confirmed that the conversation took place, describing the talks as an "ongoing process".
The development comes after a spokesman for Corbyn suggested British troops were "escalating tensions" in eastern Europe.
"Jeremy has expressed concerns about that being one of the escalations of tensions that have taken place," the spokesperson told journalists.
The comments were in reaction to the news that the UK government is to send 800 troops to Estonia as part of Nato's task force in the Baltic states, which border Russia.
Griffith, who recently hinted that a Labour government would increase defence spending, said she was "absolutely furious" after learning of the spokesperson's remarks.
"I think it's very important for Nato to be absolutely clear, following what has happened in Ukraine, that we are standing together as Nato nations and there is no way that we would tolerate any attack on any one of our member states," the frontbencher told the BBC.
The Ministry of Defence has also deployed RAF Typhoons to eastern Europe as part of Nato's Baltic air policing mission amid heightened tensions with Moscow.
The jets, based at Amari air base in Estonia, intercepted a Russian military transport aircraft in May.
"This is another example of just how important the UK's contribution to the Baltic Air Policing Mission is," said Michael Fallon, the defence secretary.
"We were able to instantly respond to this act of Russian aggression - demonstration of our commitment to Nato's collective defence."