The survey was conducted via phone on 1,000 adults aged 19 or older during June 1-3. It was unveiled days before President Moon is to meet his US counterpart Donald Trump in Washington later this week.

"This is a very significant change compared to the previous survey done in November last year in which as much as 64 percent of those polled expressed concerns about the bilateral relations," the research said in a report.

The report attributed the higher level of optimism to the hopes that many South Koreans are pinning on the new president who took office in May.

Of those polled, 30.6 percent said that the main focus during the upcoming summit between the allies should be placed on "building trust," followed by 24.9 percent and 20.1 percent saying that economic cooperation and coordination against North Korea should be the top priority, respectively.

About 19 percent cited the controversial issue of the deployment of the US missile defense system known as THAAD in South Korea should be the most important agenda item during the summit.

Meanwhile, with regard to the THAAD issue in particular, 55 percent expressed support for its installation, but 63.7 percent said that it requires parliamentary endorsement. (Yonhap)