James Cleverly is to meet with UK Armed Forces personnel in Estonia, ahead of a gathering of Nato foreign ministers in Oslo.
The Foreign Secretary will arrive in Tallinn on Tuesday for his first official visit to Estonia, where he is expected to meet members of the government and visit the Royal Navy's HMS Albion in the Baltic Sea.
Before the visit, Mr Cleverly, who is an Army officer in the reserves, said the UK's military is "leading the way" in standing up to Putin and Russia's "cruel and catastrophic aggression".
The war in Ukraine is set to top the agenda at the Nato gathering, while it is also likely that Sweden's accession to the alliance will be discussed ahead of a key summit in Vilnius, Lithuania, in July.
While there, the Foreign Secretary is likely to stress the UK's desire for continued close co-operation on European security, including support for Ukraine, which was invaded by its neighbour Russia last year, and the need to tackle illegal migration.
"In Estonia, across land, sea and air, British personnel are on the frontline protecting Europe's security and deterring Russia's cruel and catastrophic aggression," Mr Cleverly said ahead of the trip.
"As Nato allies, we are stronger than ever before – unified against hostility and in defence of democracy and freedom.
"Not only is our military leading the way, our diplomats are working across the globe to galvanise our partners and strengthen international efforts to ensure (Russian President Vladimir) Putin faces the consequences of his barbaric actions."
In Norway, Mr Cleverly is expected to use the informal meeting on Wednesday to push for Sweden to join Nato ahead of the summit in July.
Objections from Turkey and Hungary have so far slowed the process for Swedish membership.
Mr Cleverly's stop-off in Estonia will also see him speak to figures from the country's technology sector and visit a school for children of Ukrainian refugees.