WASHINGTON -- The United States maintains a whole range of responses it may take when necessary against North Korean provocations, a Department of Defense spokesperson said Tuesday.

Brig. Gen. Pat Ryder also said the US continues to closely monitor the recalcitrant country for actions that may warrant such a response.

"In terms of how we respond to individual provocations, for example, missile launches, we are going to maintain a whole range of potential responses," he said when asked why the US did not intercept missiles fired in recent North Korean missile tests.

"As you have seen INDOPACOM (Indo-Pacific Command) say in the past when they detected those launches, those launches have been determined ultimately not to pose any threat to US forces territory or that of our allies," he added. "But it's something we will continue to work on closely or monitor closely, rather."

North Korea fired more than a dozen ballistic missiles in eight rounds of missile tests staged in just three weeks from Sept. 25.

The country has launched more than 40 ballistic missiles this year, the largest number of ballistic missiles it fired in a single year.

The recent series of North Korean provocations prompted a renewed call in Seoul to redeploy US tactical nuclear weapons to South Korea.

The Pentagon spokesperson said the US troops stationed in South Korea already provide the necessary deterrence.

"We have more than 28,000 US forces already stationed on the peninsula. I think that is a signal of our commitment to our defense relationship and our security cooperation with the people of the Republic of Korea," he said, adding. "It's very long standing and will remain long standing."

Ryder also reiterated that the US-South Korea alliance is defensive in nature.

"What I would say ... is our primary focus is on preserving a free, peaceful Indo-Pacific. The relationship between the United States and the Republic of Korea is about defense and it's about preserving peace," he said of the alliance, referring to South Korea by its official name.

"It's not meant to escalate. It's not meant to create more consternation or instability in the region, and certainly the actions by North Korea are doing just that," added Ryder.

North Korea earlier claimed its recent missile launches had been provoked by joint military exercises of South Korea and the US.

The US has rejected the claim, partly by saying that it joint military drills with South Korea have been held regularly and are strictly defensive in nature. (Yonhap)