The United States partially lifted its ban on the sale of lethal weapons to Vietnam Thursday, easing a three-decade embargo, according to media reports. The policy shift was announced after Vietnam's deputy prime minister and foreign minister, Pham Binh Minh, met with U.S. Secretary of State John Kerry in Washington.

“The State Department has taken steps to allow for the future transfer of maritime security-related defense articles to Vietnam,” State Department spokeswoman Jen Psaki said. “Our security relationship remains under constant review. Clearly there is more work that needs to be done in areas like human rights, and that's one thing that was conveyed during the meeting, and this is of course a partial lifting.”

The aim of lifting the ban on the sale of weapons was to help Vietnam patrol and defend itself against increasing expansionism by China in the South China Sea, senior State Department officials told Al Jazeera. But they denied that it was an anti-China move and added that the decision was taken after Vietnam showed some progress on human rights issues.

Meanwhile, a number of rights groups, including Human Rights Watch, criticized the decision.

“Vietnam has hardly earned this reward,” John Sifton, the Asia advocacy director for Human Rights Watch, said, according to media reports. “Vietnam’s record on political prisoners is bad and getting worse. … They are still arresting people. The number of arrests and convictions has gone down from its peak in 2013, but the raw number of people going into the system is still larger than the number of people being released.”

The lifting of the arms embargo is expected to boost trade between the two countries, which currently stands at nearly $20 billion a year, according to a BBC report.