SYDNEY, Australia — The American defense secretary, Mark T. Esper, said Saturday that he was in favor of deploying ground-based missiles to Asia, a day after the United States formally pulled out of a Cold War-era arms treaty that directly limited such weapons.
Mr. Esper, speaking to reporters on his way to Australia, said he would like to see the deployment within “months” but did not specify an exact timeline, the types of weapons the United States would deploy and where exactly they would be positioned.
“These things tend to take longer than you expect,” Mr. Esper said.
Such a move would be likely to anger China and North Korea, two countries that have long opposed the deployment of American military hardware anywhere near their borders, and would most likely prompt further consternation from allies that Washington was veering dangerously close to starting a new arms race.
In 2018, the United States announced it would withdraw from the 1987 Intermediate-Range Nuclear Forces agreement, known as the I.N.F. treaty, after accusations that Russia had long dodged the treaty by repeatedly deploying nuclear-capable, medium-range missiles that could travel within the agreement’s prohibited range.
On Friday, the United States formally did so, months after Russia said it would suspend its observation of major aspects of the pact in a “symmetrical” response.
The demise of the treaty left a major hole in NATO’s defense, and the world body said on Friday that it would respond in a “measured and responsible way” to a deployment of missiles by Moscow that violated the pact.
The accord banned land-based missiles that could travel 310 to 3,417 miles. Russia has repeatedly denied breaching the pact.
On Saturday, Mr. Esper was careful to say that the deployment of any American missiles to Asia would be “conventional” in nature and within “I.N.F. range.”
Despite his pledge to field shorter-range missiles to the region, that has not stopped the Pentagon from looking toward an I.N.F.-free future in which longer-range ground-based missiles might soon be tested and deployed.
But Mr. Esper also expressed caution on Saturday over how long those types of weapons would take to reach the field.
“I honestly can’t recall if it’s 18 months or longer, but my sense is it would likely take longer,” Mr. Esper said. “It’s fair to say, though, that we would like to deploy a capability sooner rather than later.”
With China wielding an array of weapons capable of striking Taiwan, Japan, India and Guam, and the recent North Korean tests of short-range ballistic missiles that have been compared to Russia’s nuclear-tipped Iskander ballistic missile, experts say they believe that a new arms race may be on the horizon.
One remaining bulwark against such a move is New START, a treaty between the United States and Russia that dictates the number of strategic weapons that can be deployed. But the agreement is unlikely to be renewed when it expires in less than two years.
When asked about the fate of New START, Mr. Esper said that “we need to take a serious look at the treaty” and make sure that it is still within the United States’ interests.
If the United States wants to avoid an arms race, Mr. Esper said, efforts should be made to incorporate other countries into the treaty.