The UK is doubling its troop presence in Estonia in response to tensions involving Russia, with extra personnel and hardware being sent to the Baltic nation.
Personnel, tanks and armoured vehicles began moving to the country on Wednesday.
A battlegroup from Royal Welsh is leaving bases in the UK and Germany, and is due to arrive in Estonia within the next week.
Other equipment being deployed includes:
- Apache helicopters to conduct exercises in eastern Europe
- Four additional Typhoon jets that have landed in Cyprus tasked with patrolling the skies over eastern Europe
- Warship HMS Trent, which has started patrols in the eastern Mediterranean Sea with NATO allies
- HMS Diamond is also preparing to set sail from the UK for a similar role.
The Ministry of Defence says most of the 350 Royal Marines who deployed to Poland this month have already arrived, with 1,000 extra British personnel at readiness in the UK if needed for a humanitarian response.
Defence Secretary Ben Wallace said: "Alongside our NATO allies, we are deploying troops and assets on land, sea and air to bolster European defences in response to the build-up of Russian military forces on the border of Ukraine.
"NATO and our allies have been clear that an invasion of Ukraine will be met with severe consequences.
"De-escalation and diplomacy remain the only path out of this situation," he added.
NATO Secretary General Jens Stoltenberg said on Wednesday he believes Russia is continuing its military build-up around Ukraine's borders.
Russia, however, has said some of its troops stationed near the Ukraine border are returning to their bases and has repeatedly denied it is planning to invade.