Leaders of the bipartisan Congressional Singapore Caucus have stressed the importance of maintaining the close relationship between the United States and Singapore.

Republican congressman and caucus co-chair Bradley Byrne, speaking at a reception hosted by visiting Minister for Foreign Affairs Vivian Balakrishnan on Tuesday, said Singapore is "one of the most impressive places I have ever been (to)".

"American security interests follow our trading interests, it has always been so. We need to go and tell our constituents that we, the United States, benefit from our free trading system, from the openness of the sea lanes of the world and particularly the openness of sea lanes in that part of the world," he said.

Mr Denny Heck, the Democratic caucus co-chair, called Singapore "an incredible success story".

"There is no future for America on the global stage if it does not come to terms with how it is going to face… Asia," he said.

"There can't be a coherent relationship with China without also having a coherent relationship with the nations of Asean, and there can't be (a) relationship with Asean if we do not have a strong relationship with the thought leader among the Asean nations and that's Singapore," he added.

Dr Balakrishnan told the congressmen that part of the reason for Singapore's "reasonable measure of success" had been the US presence in Asia.

"Particularly in South-east Asia your presence over the last 70 years has ensured that the rules-based order prevails, a belief in free trade, open markets, and that's made all the difference," he said.

Recalling that Vice-President Mike Pence had noted, during his visit to Jakarta in April, that US exports to South-east Asia exceeded US$100 billion (S$138 billion) a year and supported half-a-million jobs in the US, Dr Balakrishnan said: "We also need to make the argument that it creates jobs, opportunities, for Americans wherever they are."

Republican Ted Yoho, chair of the House sub-committee on Asia and the Pacific, said his panel would remain "deeply committed" to US engagement in South-east Asia.

Also on Tuesday, Dr Balakrishnan met Deputy Secretary of State John Sullivan and they reaffirmed the excellent state of Singapore-US relations, underpinned by strong economic and defence relations, as well as close people-to-people ties, Singapore's Ministry of Foreign Affairs (MFA) said yesterday.

Dr Balakrishnan was scheduled to meet, among others, Deputy National Security Adviser for Strategy Dina Powell and Senate armed services committee chairman John McCain yesterday.

He will then travel to New York for the high-level United Nations Conference to Support the Implementation of Sustainable Development Goal 14, MFA said in a statement.