SEOUL, South Korea — The president of South Korea vowed on Thursday to accelerate efforts to strengthen its pre-emptive strike, missile defense and retaliatory capabilities against North Korea, and he renewed his call for the armed forces to become more independent from the United States.

In a speech to mark South Korea’s Armed Forces Day, the president, Moon Jae-in, said he would push for the South to move more quickly to retake wartime operational control of its military from its American ally. Since the Korean War in the early 1950s, the terms of the countries’ alliance have called for an American general to command the South’s 650,000-member military should war break out.

Mr. Moon and other liberals have campaigned for South Korea to play a greater role in the alliance, and they have long called for the country to resume responsibility for wartime command as soon as it can feasibly do so. But the idea has gotten more public support as remarks by President Trump have led many South Koreans to doubt his commitment to defend their country.

Mr. Moon said Thursday that a more self-reliant military could make itself stronger and more feared by North Korea. But he also said the South should strengthen its alliance with Washington. An aide to Mr. Moon said this week that the allies were working on ways to move strategic American military assets into the region more frequently, to help deter North Korea.