FOUR US warships will be operating out of Singapore by 2018, up from one currently, said a senior US Navy officer yesterday.

Rear-Admiral Charles Williams told Agence France-Presse that there will soon be up to four US Navy littoral combat ships (LCS) in Singapore. These vessels are designed to fight in coastal areas similar to South-east Asian waters.

"We envision four ships here by May 2017 to some time in 2018... but I think what you have is that by 2018, four LCS ships will be rotationally deployed... to Singapore," he said.

Rear-Adm Williams, who commands the 7th Fleet's Task Force 73, was speaking to reporters aboard the USS Fort Worth - an LCS on a 16-month deployment to South-east Asia.

The USS Fort Worth is the second LCS deployed here to support the US rebalance to the region, under an initiative announced at the Shangri-La Dialogue in 2011.

The first LCS, the USS Freedom - the first of four such ships that Singapore has allowed to operate in its waters - completed an eight-month stint last year.

Fort Worth, which is used for operations close to shore, arrived at Changi Naval Base last December, more than a month after leaving its home port, San Diego.

The warship, which carries an MH-60R Seahawk helicopter and one MQ-8B Fire Scout unmanned aircraft system, is operating as part of a 16-month rotational deployment to the US 7th Fleet, which conducts forward- deployed naval operations in the region.

It is conducting patrols and training with regional navies during exercises, such as the Cooperation Afloat Readiness and Training, in South and South-east Asia. Three groups of crew will be rotated every four months to minimise crew fatigue, allowing the ship to be deployed twice as long as a typical US Navy ship deployment.