Data compiled by Bloomberg show a growing number of shipments without declared destinations, a sign that traders are wary of breaching tightening U.S. restrictions. “There are several factors, like the new U.S. sanctions against Rosneft and Lukoil,” said Wojciech Jakóbik, founder of the Energy Security Center in Warsaw. “Another factor is American pressure to diversify away from Russian supplies.” Fewer tankers have been leaving Russian ports since late October, suggesting that sanctions may finally be starting to bite. But experts caution the effect could fade unless Washington keeps up the pressure.