U.S. President Donald Trump will not go to the heavily fortified demilitarized zone (DMZ) on the border of North Korea and South Korea during his Asia trip, a senior administration official said on Tuesday.

"The president is not going to visit the DMZ. There is not enough time in the schedule," the official told reporters in a background briefing.

Instead, Trump will be the first American president to visit Camp Humphreys, a military installation south of the South Korean capital of Seoul.

"We thought that would make more sense in terms of its messaging, in terms of the chance to address families and troops there," the official said.

U.S. Defense Secretary Jim Mattis visited the demilitarized zone that divides the Korean Peninsula last week and Vice President Mike Pence made the same trip in April.

The official, speaking on customary condition of anonymity in briefing reporters, noted the two Trump administration forays to the zone.

"It's becoming a little bit of a cliche, frankly," the official said.

Trump leaves for his first trip to Asia this week and is expected to arrive on October 5 in Tokyo.

Separately, two U.S. officials said a decision may be made for the three aircraft carriers currently in the Asia Pacific region to carry out an exercise to coincide with Trump's trip. The officials said no decision had been made, but it would be the first exercise with three U.S. aircraft carriers in the region since 2007.

A senior State Department official, speaking on the condition of anonymity, said the buildup of naval forces was part of the military component of the Trump administration's strategy to put "maximum pressure" on North Korea, which includes sanctions and diplomatic isolation.

Earlier on Tuesday, the State Department welcomed a decision by China and South Korea to resume normal ties after a year-long standoff over a decision by Seoul and Washington to deploy a missile defence system to counter North Korea's nuclear programme.