Prime Minister Boris Johnson is due to visit the region next week, and also will speak to Vladimir Putin by phone.
Johnson is considering the biggest possible offer to members of the NATO defence pact in the Nordics and Baltics, which would double troop numbers and send defensive weapons to Estonia, his office said.
"This package would send a clear message – we will not tolerate destabilising activity, and we will always stand with our NATO allies," Johnson said in a statement.
"I have ordered our Armed Forces to prepare to deploy across Europe next week, ensuring we are able to support our NATO allies."
Officials will finalise the details of the offer in Brussels next week, with ministers discussing the military options on Monday.
Stepping up diplomatic efforts after facing criticism for not doing enough, Johnson will make a second trip to meet NATO counterparts early next month, his office said.