Russia is “really gearing up for war” with Ukraine, Lithuanian Foreign Minister Gabrielius Landsbergis said in Brussels on Monday.

“I still have the feeling that we are not taking this seriously enough, including what’s going on in Lithuania as well,” Landsbergis told reporters in Brussels after the EU foreign minister’s meeting on Monday.

Some 100,000 Russian troops have amassed near the Ukrainian border in recent weeks. NATO has warned Moscow it would face large-scale strategic and economic consequences in case of an invasion.

Russia rejects such concerns and says its moves are aimed at preventing Ukraine from joining NATO.

Landsbergis warns Russia wants more than just to “rattle its saber” or cause temporary unrest in the region.

“Judging from warnings from our partners and colleagues, they want to change the region’s strategic landscape that has developed over the past decades,” Lithuania’s top diplomat said. “And this is very dangerous, and dangerous for Lithuania.”

Landsbergis wrote on Facebook that the West, willing to avoid a war, might be ready for major strategic concessions, adding that the existing escalation is happening because Ukraine is increasingly slipping away from “Putin’s world”.

Since Russia’s military action could take place not far away from Lithuania, the latter must prepare independently and in cooperation with partners, Landsbergis said.

“We need to get ready for possible sanctions as well. It must be clear what Russia could face if it crosses Ukraine’s border again,” he said, adding that the West should “not play Russia’s game”.

“The open-door policy is both NATO and the EU’s gravitational powers and the catalyst of positive changes,” the minister said.

Security of the Baltic Sea region must be bolstered in response to the existing threat, Landsbergis added.