U.N. Secretary-General António Guterres said during an official visit to non-NATO member Moldova that the consequences of Russia’s war against Ukraine escalating are “too frightening to contemplate”.

Guterres, who arrived in Moldova’s capital Chisinau on Monday, said in a joint press conference with Prime Minister Natalia Gavrilita, that the impact of Russia’s war in neighboring Ukraine “is profound and far-reaching”.

The U.N. chief’s visit to Moldova, one of Europe’s poorest countries, which has a population of about 2.6 million people, follows a series of unsettling incidents that have rocked Moldova’s pro-Russia breakaway region of Transnistria, which has put officials in Chisinau on high alert.

In late April, three men launched grenades at the region’s state security office, and two large broadcast antennas were downed a day later. On Friday, Police in Transnistria said explosive devices were dropped from a drone leaving 1-meter-deep craters near a village.

“I am deeply concerned about the continuation and possible spread of the war Russia is waging in Ukraine”, - Guterres said, adding that Moldova’s sovereignty and territorial integrity “must not be threatened or undermined”.