HANOI (Reuters) - In a post-war first, the United States will send an aircraft carrier to Vietnam, Hanoi's defense ministry said on Thursday, in a major demonstration of deepening military ties between the former enemies more than four decades after the Vietnam War.

The announcement of the proposed visit, that could bring the most U.S. forces to the country since the conflict ended in 1975 came during a two-day visit by U.S. Defense Secretary Jim Mattis to Hanoi which was expected to focus on shared concerns about China.

The arrival of a U.S. aircraft carrier in Vietnam is expected to be welcomed by an emerging network of countries who are nervously eyeing China's military rise, particularly its assertive stance and island-building activities in the South China Sea, a vital global trade route linking Northeast Asia with the Middle East and Europe.