The US military will retain a "strong presence" in the Middle East despite a strategic shift to Asia, Defence Secretary Leon Panetta said on Tuesday during a visit to Kuwait.

The United States plans to deploy a majority of its naval fleet to the Asia-Pacific along with other advanced weaponry but Panetta insisted that a robust American force would remain in place in the Middle East.

Panetta spoke to reporters aboard his plane travelling to Kuwait City on a two-day visit to discuss bolstering security ties amid tumult in the region and tensions with Iran.

"Let me assure you that the United States is strong enough that we can maintain a strong presence in the Middle East as well as in the Pacific," he said.

He acknowledged that the United States had to be "flexible" in managing its forces in a more austere era and that it would have only one aircraft carrier in the Middle East for about two months to allow for maintenance work on another carrier, the USS Nimitz.

The American military still had nearly 50,000 troops and warships positioned across the region, he said.

"But in the end, I am very confident that we're going to be able to maintain the ships and forces we need in order to respond to any contingency."

The United States has deployed more ships and aircraft in the Gulf over the past year after Iran threatened to close the strategic Strait of Hormuz if Western countries boycotted its oil exports.

Panetta held talks on Tuesday with Kuwait's emir, Sheikh Sabah al-Ahmad Al-Sabah, at his residence along with the crown prince, the prime minister, defence minister and senior officials, the official KUNA news agency reported.

"The secretary expressed strong confidence in the long standing US-Kuwaiti defence relationship, and in the ability of both countries to work together to address common security challenges in the Gulf region and beyond," Panetta's spokesman, George Little, said in a statement.

Panetta also "underscored the importance the US defence strategy places on the Middle East," it said.

He "commended" the emir for Kuwait's role "in fostering peace and security in the region."

Panetta and the emir also discussed the crisis in Syria, cyber security threats, Kuwait's recent parliamentary elections and "ongoing commitment to the rule of law," it said.

The visit, the first by a Pentagon chief to Kuwait in five years, coincides with a wave of protests in the oil-rich Gulf state, with thousands of opposition demonstrators demanding fresh elections amid a bitter dispute over amendments to the country's electoral law.

Kuwaiti activists have called for protesters to camp outside parliament next Saturday on the eve of its opening session.

During the visit, which ends on Wednesday, Panetta also plans to meet some of the 13,500 US troops stationed in the Gulf state to thank them for their service ahead of the Christmas holidays.

Speaking to reporters earlier, Panetta said the two countries "share a history of cooperation that goes back to the first Gulf War" in 1991 when a US-led coalition ousted Iraqi occupation forces.

"Our presence in Kuwait and throughout the Gulf helps enhance the capabilities of partner nations, deters aggression and helps ensure that we're better able to respond to crises in the region."