HANOI, Vietnam — The Vietnamese government has lashed out against the presence of a Chinese oil rig in the disputed waters of the South China Sea, the latest in what Vietnam says are a series of provocative actions by Beijing this month.

While the dispute raised tensions between the Communist neighbors, there were no signs yet of the heated escalation that characterized a similar episode in 2014, when relations between the two countries plummeted and anti-Chinese demonstrations spiraled into deadly riots.

Late on Tuesday, the Vietnamese Foreign Ministry said that Haiyang Shiyou 981, the same rig that was at the center of the 2014 feud, had entered disputed waters in the South China Sea on Saturday, according to a statement on the ministry’s website.

The rig was still 25 miles from an “assumed median line” between the two countries, the statement said, but it was in “an overlapping area between the two continental shelves” of Vietnam and Hainan Island, China, which “has not yet been delimited.”