President Obama is considering broadly expanding weapons sales to Vietnam in a move aimed at strengthening ties with Hanoi and boosting regional defenses against China's growing clout.
As Obama prepares to visit Vietnam this weekend, U.S. officials say he is leaning toward a partial lift - but has not ruled out a full suspension - of the ban on arms sales begun during the U.S. war in Vietnam and eased slightly in 2014.
At the same time, the Vietnamese government is examining a request to grant the U.S. Navy greater access to Cam Ranh Bay, a major supply point for the U.S. military during the Vietnam conflict, and a port with direct access to the increasingly contested islands in the South China Sea.
Obama has not made a final decision, administration officials say. But the changes, if approved, would mark a dramatic upgrade in U.S. relations with an authoritarian Communist government that the State Department considers a routine abuser of human rights.
White House concerns about Vietnam's lack of progress on civil liberties and political freedoms have held up a decision to end the ban on arms sales -- first imposed on North Vietnam in 1964 and later extended it to cover the entire country after the U.S.-backed South Vietnamese government fell in 1975.
In the 1990s, President Clinton lifted the trade embargo with an executive directive to his agencies but left in place restrictions imposed by Congress to prohibit sales of weapons and certain high-technology material. The two countries restored diplomatic relations in 1995.
In 2014, Obama eased restrictions on sales of maritime surveillance and security systems to Vietnam
That change has allowed the sale of U.S. patrol boats with mounted machine guns, search-and-rescue vessels and naval reconnaissance aircraft.
Last June, the U.S. pledged $18 million to help Vietnam buy American-made Metal Shark patrol boats, a deal that came through after a Chinese navy ship rammed a Vietnamese patrol boat in the South China Sea.
U.S. officials say Vietnam is expected to use about $12 million in U.S. foreign military financing this year to buy small patrol boats, communications equipment and English-language training.
Obama now is looking at wiping out other parts of the ban, according to senior defense officials and others briefed on the deliberations.
Closer military ties between the two former enemies dovetail with Obama's steady push since 2011 for a strategic U.S. "rebalance" toward Asia and the Pacific.
In recent months, the administration has refreshed its defense treaty with Japan and has sought congressional support for a 12-nation free trade agreement known as the Trans-Pacific Partnership, a priority for the White House.
It also has urged China to settle territorial disputes with Vietnam and other countries in the resource-rich South China Sea. The Pentagon has sent U.S. warships and surveillance planes close to several contested islands and reefs where China has built airstrips and other facilities.
National security experts say China is unlikely to look favorably on expanded U.S. weapons sales to neighboring Vietnam, or warmer ties between Hanoi and Washington.
"It's safe to say the Chinese will react negatively," said Michael J. Green, senior vice president for Asia and Japan chair at the Center for Strategic and International Studies.
Defense Secretary Ashton Carter, who visited Vietnam last June, told the Senate Armed Services Committee last month that he would support lifting restrictions on the sale of weapons.
The committee's draft of the annual defense authorization bill includes language that encourages lifting the ban as well. It would create a process to review Vietnam's progress on human rights and to ensure the weapons aren't used against Vietnamese civilians.
Vietnam now buys most of its military equipment from Russia, its longtime ally. Lifting the embargo could be a boon to U.S. arms makers as Hanoi looks to modernize its Soviet-era aircraft.
Sen. John McCain (R-Ariz.), a Vietnam veteran and chairman of the Senate Armed Services Committee, said he expects Obama to lift the embargo and that Hanoi will grant the U.S. Navy greater access to Cam Ranh Bay.
McCain, who spent five years as a POW in Hanoi during the war, said it's time for Washington to fully lift its ban on arms sales.
"Given the Chinese aggressive behavior in the region, it should not be inappropriate to allow [Vietnam] to have weapons with which to defend themselves particularly in the maritime area ... where the potential for confrontation exists," McCain said in an interview.
Obama administration officials have pushed Vietnam to improve its treatment of political opponents and stop other human rights abuses before Obama departs Saturday on a week long trip to Vietnam and Japan.
The State Department's annual report on human rights for 2015 said Vietnam had continued to enforce "severe government restrictions of citizens' political rights, particularly their right to change their government through free and fair elections," among other abuses.
"We continue to stress to Vietnam that continued progress on human rights will be important to progress in the overall relationship, including on the lethal weapons ban," said David McKeeby, spokesman for the State Department's bureau of political-military affairs.
On Capitol Hill. Rep. Loretta Sanchez (D-Santa Ana) offered an amendment to a defense bill being considered by the House this week that would urge the White House to make any expansion of arms sales to Vietnam contingent on human rights progress.
"I'm just a little bit worried about weapons deals that might be made given that the human rights conditions continue to be terrible in Vietnam," Sanchez said.
Sen. Patrick Leahy (D-Vt.), who has expressed concern about lifting the embargo, said doing so would "send a not-too-subtle message to China at a time when it is threatening regional stability in the South China Sea."
"But it should not open the floodgates for sales of lethal equipment," Leahy said. "Those decisions are made on a case-by-case basis ... [and] should reflect an assessment of the relevant factors including progress by the Vietnamese government in protecting human rights."
Human Rights groups argue that it's too soon to fully lift the ban.
"They have done very little to deserve the reward," said John Sifton, the Asia advocacy director at Human Rights Watch. "They have been asked over the last three to five years to demonstrate progress in legal reforms, to repeal laws criminalizing criticism of the government, to release political prisoners. In response, they have done almost nothing."
Among other concessions, advocates want Vietnam to release Montagnard Christians, a persecuted ethnic minority, plus bloggers and dissidents held by the government. There are 102 known political prisoners from those groups.
2:55 p.m.: This story has been updated with new details.