Defence Secretary Philip Hammond will join his Nato counterparts to discuss the crisis in Ukraine today.
Ahead of Prime Minister David Cameron's meeting with Russian president Vladimir Putin on Friday, Mr Hammond will sit down with Nato ministers to discuss the long-term implications of Russia's "illegal actions" in Ukraine, according to Nato's website.
At the two day summit in Brussels, Mr Hammond is likely to hear fears from allies such as Poland that normal relations are being resumed with Moscow.
The talks come ahead of Mr Cameron's meeting with Mr Putin after the two leaders attend commemorations of the 70th anniversary of the D-Day landings in Normandy on Friday.
Mr Cameron is expected to emphasise the importance of dialogue between Moscow and newly elected Ukrainian president Petro Poroshenko. His official spokesman dismissed suggestions that the talks were an attempt to "make peace" with Mr Putin.
The PM will come face-to-face with Mr Putin after also going to Brussels to meet US President Barack Obama and the other G7 leaders, with Russia's annexation of Crimea and the ongoing hostilities in the east of Ukraine sure to be high on the agenda.
The meeting was hastily arranged after they decided to boycott a planned summit of the G8 - which includes Russia - that Mr Putin was due to host in Sochi this week.
Mr Obama is expected to press European leaders this week to keep up pressure on Russia over its behaviour towards Ukraine.
While there are signs that Russia has begun to move troops away from the Ukrainian border, it still faces criticism for doing too little to ease tensions in the east of the country where deadly clashes continue between pro-Russia separatists and government forces.
Around 100 armed insurgents were reported to have attacked a border guards' camp in Luhansk in the latest clashes
It also comes amid heightened tensions between London and Moscow over reported comments by the Prince of Wales comparing Mr Putin's actions in Ukraine with those of Adolf Hitler.