KYIV, April 26 - Russian missile fire knocked out a strategic railroad bridge along a route that links southern Ukraine’s Odesa port region to neighboring Romania, a NATO member, The Associated Press reported citing the Ukrainian authorities. No injuries were reported.

The attack on the bridge near Odesa — along with a series of strikes on key railroad stations a day earlier — appears to mark a major shift in Russia’s approach. Until now, Moscow has spared strategic bridges, perhaps in hopes of keeping them for its own use in seizing Ukraine. But now it seems to be trying to thwart Ukraine’s efforts to move troops and supplies.

The southern Ukraine coastline and Moldova have been on edge since a senior Russian military officer said last week that the Kremlin’s goal is to secure not just eastern Ukraine but the entire south, so as to open the way to Trans-Dniester, a long, narrow strip of land with about 470,000 people along the Ukrainian border where about 1,500 Russian troops are based.

It was not clear who was behind the blasts in Trans-Dniester, but the attacks gave rise to fears that Russia is stirring up trouble so as to create a pretext to either invade Trans-Dniester or use the region as another launching point to attack Ukraine.

Ukrainian President Volodymyr Zelenskyy said the explosions were carried out by Russia and were “designed to destabilize,” with the intention of showing Moldova what could happen if it supports Ukraine.

Austin, the U.S. defense secretary, said the U.S. was still looking into blasts and trying to determine what was going on, but added: “Certainly we don’t want to see any spillover” of the conflict. (ap/ez)