The Pentagon has announced the deployment of an additional 800 troops to South Korea, along with combat tanks and other military hardware, as Washington seeks to counter any regional threats from North Korea.
Tuesday's deployment announcement came as U.S. Secretary of State John Kerry met in Washington with his South Korean counterpart, Yun Byung-se. Kerry used the meeting to assure Yun of Washington's commitment to South Korea's nuclear defense, in his words, "so that we are prepared to face any threat."
"The United States and the Republic of Korea stand very firmly united without an inch of daylight between us - not a sliver of daylight - on the subject of opposition to North Korea's destabilizing nuclear and ballistic missile programs and proliferation activities, and the international community stands with us."
Kerry said the two diplomats are "deeply focused on the challenge of North Korea, particularly with events that have taken place in recent weeks" in Pyongyang.
His comments appeared to reference a recent political purge that included the execution of the uncle of North Korean leader Kim Jong Un.
The killing in December of Jang Song Thaek, a powerful member of the politburo, is seen by some Western analysts as a move by Kim to consolidate power, and by others as evidence of political instability within the North Korean hierarchy.
A Pentagon statement said elements of the 1st Army Battalion from Ft. Hood, Texas will deploy to Camps Hovey and Stanley in South Korea by February 1.
Cedric Leighton, a retired Air Force officer and risk management consultant, tells VOA the battalion has extensive combat experience in Afghanistan and Iraq. They are being deployed relatively close to the demilitarized zone, sending what Leighton calls a "clear signal" to the North.
"We're reassuring the South Koreans that we will continue to maintain a trip-wire of American forces on the Korean peninsula. And we're also going to not only put military forces there, but we're going to put military forces that are combat-experienced in that area. And that is a clear signal to the North not to engage in any adventures that would potentially bring conflict to the Korean peninsula."
A Pentagon spokesman described the deployment as long-planned and part of an ongoing shift of U.S. military power toward the Asia-Pacific region.
The White House has in recent months moved to reassure its Asian allies of its commitment to the diplomatic, economic and military pivot toward Asia.
But Brad Glosserman of the Hawaii-based Pacific Forum tells VOA the troop deployment calls into question the geographic focus of the Asia rebalance.
"If you go back to the original language about the rebalance, the argument was always that the Americans have gotten Northeast Asia well, and that we wanted to sort of refocus and provide sustained attention to Southeast Asia. This actually goes up a bit up against that grain."
Glosserman also says the move raises questions about what form the Asia pivot will take, since White House officials have stressed it will not have a military-first focus.
Since the pivot was formally announced in 2011, the U.S. has broadened and deepened its economic and military alliances throughout Asia. The strategy is seen by many as providing a counterweight to the rising influence of China, though U.S. officials deny this.