Ukrainian officials say that Russia, which has positioned more than 100,000 troops around three sides of Ukraine, is stepping up a destabilization campaign involving cyberattacks, economic disruption and a new tactic: hundreds of fake bomb threats.

Russian forces and their proxies already control portions of Ukraine and frequent skirmish with government forces. The aim of Moscow’s intensifying hybrid campaign, Ukrainian officials say, is to weaken their country and sow panic, potentially provoking discontent and protests of the kind Russia fomented in eastern Ukraine in 2014 to justify its interventions there. U.S. and U.K. officials said last month they uncovered coup plots intended to install a puppet pro-Russian government.

The tactics illustrate how Russian President Vladimir Putin can maintain pressure on Ukraine without escalating to a shooting war that could provoke sanctions from the West. Ukrainian officials say a destabilization campaign is more likely than a large-scale invasion.