"The most important thing is to demonstrate that South Korea and the US closely coordinate over the North with the same objectives," said Yun Duk-min, former chancellor of the Korea National Diplomatic Academy. "It would be very bad for any differences to be exposed."

Chun Young-woo, who served as former President Lee Myung-bak's senior secretary for foreign affairs and national security, echoed the view.

"It is most important to manage things without causing any cacophony (during Trump's visit and the summit)," Chun said.

"Resolving any existing misunderstanding and mistrust through the meeting is in and of itself important, but more importance should be attached to keep such feelings from brewing out."

There have been cases in which Moon and Trump have showed their apparent differences on how to deal with the recalcitrant North.

The Seoul government has been seeking to resume talks with the North under President Moon's so-called dual track approach that puts emphasis both on pressure and dialogue to resolve the nuclear problem.

The Trump administration, meanwhile, seems to be adamant that there should be meaningful change in the North's behavior before any talks start.

Ratcheting up tensions, Trump has also engaged in a war of words with North Korea, in which both suggested possible military action against each other.

Against this backdrop, concerns mounted that South Korea could be bypassed from any unilateral action by the US against the North and the two allies might not be on the same page in dealing with the reclusive state.

"No matter what, all will boil down to the North's nuclear weapons and the alliance between South Korea and the US when Trump visits here," said Kim Sung-han, a professor at Korea University. "Heeding the concerns that the two countries are not on the same wavelength, the leaders must make sure that it is not the case."

Experts are a little divided over how the Seoul government should react to the US' pressure-oriented approach towards the North.

Some said that it would not be good for Trump's visit and the summit to be used as a venue to vent differences on the front, urging the Moon government to restrain from emphasizing its push for talks with the North.

Others claimed that the allies should send out a message that they will closely cooperate in putting the maximum amount of pressure on the North so as to bring it to talks on its denuclearization. 

They still worried that the two could run into some discord over such sensitive issues as the ongoing renegotiation of the five-year-old free trade agreement and upcoming talks on cost-sharing of the US troops stationed in South Korea.

Trump has accused the FTA of destroying many American jobs and causing a huge deficit to his country. He has also demanded South Korea take up more of the cost of maintaining about 30,000 US troops on its soil.

Experts called for the Seoul government to be well prepared for any possible unexpected remarks by Trump on those issues during his trip here, which could derail efforts to demonstrate unity and a strong alliance through their summit.  (Yonhap)