Vietnam rejected US Defense Secretary Ashton Carter's demand to stop land reclamation in the South China Sea, saying the activities were not aimed at expansion.
Carter called for an "an immediate and lasting halt to land reclamation by all claimants" at a security summit in Singapore on Saturday. The United States previously accused China of "manufacturing sovereignty" by reclaiming and consolidating islands in the disputed region.
"We have some activities to enhance and consolidate the islands that are under our sovereignty. We do not expand the islands, we just consolidate to prevent erosion because of waves," Vietnam's Defense Minister Phung Quang Thanh said after talks on Monday.
Vietnam also has soldiers stationed on 21 islands and reefs in the disputed region, according to Thanh. A US military source told Reuters that Carter did not receive an explanation over what Vietnam considers maintenance versus new expansion.
"On the submerged islands, we only built small houses, which can accommodate a few people and we are not expanding. The scope and characteristic of our work is purely civilian," Thanh added.
Carter also pledged $18 million for Vietnam to buy coast guard vessels. The US banned selling arms to Vietnam not related to maritime security or surveillance over what the US considers Vietnam's "human rights" issues.
The US use of Agent Orange, since banned by the Geneva Convention, led millions of Vietnamese citizens to suffer from health problems including disabilities and birth defects. Residue from the agent continues to contaminate Vietnam's agricultural lands and pose a threat to nearby residents and the country's food supply.
