U.S. Defense Secretary Lloyd Austin looked to improve military relations with Vietnam during talks Thursday.The closer security relations come more than 40 years after the Vietnam War ended in 1975.President Joe Biden's administration, however, has said there are limits to the relationship unless Hanoi makes progress on human rights.Before a meeting with the Vietnamese defense minister in Hanoi, Austin said the United States is not asking Vietnam to choose between countries."One of our central goals is ensuring that our allies and partners have the freedom and the space to chart their own futures," Austin said.On Sunday, the U.S. shipped 3 million doses of the Moderna COVID-19 vaccine to Vietnam.That raised the amount given to Vietnam by the U.S. through the global COVAX program to 5 million doses.