People in Seoul watch a news broadcast on North Korea's test launch of an intercontinental ballistic missile on July 29, 2017. (Ahn Young-joon/AP)

A large majority of Americans consider North Korea's nuclear weapons program a critical threat toward the United States, according to a new poll.

However, they remain divided on which policy would best contain that threat — and, for the first time in almost 30 years, a majority of Americans were found to support military action if North Korea attacked South Korea.

The poll, conducted by the Chicago Council on Global Affairs, offers a glimpse of how Americans are responding to the rapidly evolving tensions with Pyongyang. Just two years ago, 55 percent of Americans listed North Korea as a critical threat facing the United States. Now 75 percent do, making it among the greatest perceived threats in the poll.

And, notably, though many analysts now suggest that persuading North Korea to give up its nuclear weapons may be impossible, few Americans are willing to accept allowing North Korea to keep the nuclear weapons it already has. Only 21 percent say they would support an agreement in which North Korea halted its nuclear program but did not give up its existing weapons (17 percent of Republicans and 26 percent of Democrats).

Even fewer — 11 percent — say they would be willing to accept a deal that would allow North Korea more nuclear weapons.

Despite the questionable success rate of sanctions already in place, 76 percent of Americans favor increasing sanctions on North Korea with strong bipartisan agreement (84 percent of Republicans and 76 percent of Democrats), while 68 percent support placing sanctions on Chinese banks and other entities that do business with North Korea.

After the United Nations voted Aug. 5 to punish North Korea for missile tests, officials from the country lashed out. (Sarah Parnass/The Washington Post)

There are significant differences between Republicans and Democrats when it comes to the use of force against North Korea. Notably, 54 percent of Republicans favor airstrikes against North Korean weapons facilities vs. 33 percent of Democrats. However, both the use of airstrikes and U.S. troops to attack such facilities were supported by a minority of Americans — 40 percent and 28 percent, respectively.

Sixty-two percent of Americans were found to support the use of U.S. troops if North Korea invaded South Korea — the first time since 1990 that a majority favored backing South Korea in this way — with considerable support among Republicans (70 percent), Democrats (59 percent) and independents (61 percent). The Chicago Council suggested that the sense of a heightened threat from the North may have increased commitment to South Korea.

On Monday in the Philippines, North Korea’s foreign minister said his nation would never put its nuclear weapons or ballistic missiles on the negotiating table.

In a copy of a speech planned by Ri Yong Ho, he also warned that the North was “ready to teach the U.S. a severe lesson with its nuclear strategic force” if American forces attacked. Ri was attending a meeting of Association of Southeast Asian Nations foreign ministers and dialogue partners.

The findings of the poll largely echo those from a recent poll conducted for The Washington Post and ABC News. In that poll, a new high of 66 percent of Americans were found to believe that North Korea posed a “serious threat” to the United States, though 4 out of 10 said they did not trust President Trump to handle the issue “at all.”

The Chicago Council's analysis was based on data from a survey conducted by GfK Custom Research between June 27 and July 19. A total of 2,020 adults living in all 50 U.S. states and the District of Columbia were surveyed, with a margin of error of plus or minus 2.4 percentage points.

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Brian Murphy contributed to this story.