Andrea Thompson, under secretary of state for arms control and international security, was commenting on Washington's push to deploy the missiles in Asia following its withdrawal from a missile treaty with Russia earlier this month.
South Korea, a US treaty ally that hosts 28,500 American troops, has been cited as a candidate site, although the government has denied any plans to consider the deployment.
"That's a sovereign decision to be made by the leaders of those governments," Thompson told reporters in a teleconference. "What I can tell you is any decisions made in the region will be done in consultation with our allies. This is not a US unilateral decision. We work collaboratively with partners and allies."
Thompson added that any missile deployment would be defensive in nature, although China has reacted strongly to the suggestion by threatening to take countermeasures, triggering concerns of an arms race.
"We're looking to how to best defend American interests and those of our partners and allies abroad, and we're doing that," Thompson said. "You saw that with the discussions with the secretary of defense in the region. We've had Secretary (of State Mike) Pompeo in the region multiple times. The vice president has been to the region, and the president as well. It's just another indicator of how important this region is to this administration."
On North Korea's missile development, Thompson said the US is concerned by it but will continue to engage the regime in talks to denuclearize the country.
North Korea has conducted five rounds of weapons tests since July 25, which experts say advances the regime's short-range ballistic missile capabilities.
Still, US President Donald Trump has brushed them off as "very standard" and reaffirmed his commitment to continuing negotiations with the regime.
"I won't go into the intelligence work in this forum, but what I can tell you is we are concerned about the missile development," Thompson said, adding that the US will maintain sanctions on the North until its denuclearization.
"We'll continue to call out the DPRK on their missile testing," she said, using the abbreviation for North Korea's official name, the Democratic People's Republic of Korea.
Thompson also noted, "We'll continue to stay engaged. We want the talks to happen. We have working-level discussions and have faith and confidence that the president and Chairman Kim will engage again."
Trump and North Korean leader Kim Jong-un have held three meetings to negotiate the North's denuclearization in exchange for sanctions relief, but the talks have been stalled since Feb., when their second summit ended without a deal. (Yonhap)