Thousands of Honduran migrants whose trek toward the United States has triggered tirades from US President Donald Trump forged on Sunday after crossing a river into Mexico, marching for hours.

Mexican authorities allowed dozens of women and children from a US-bound Honduran migrant caravan to enter the country Saturday but thousands remain stranded on a border bridge between Guatemala and Mexico where riot police barred their progress.

Hundreds of people in a caravan of migrants that crossed from Honduras into Guatemala staged a dramatic bid to breach the Mexican border on Friday, as local governments began preparing to disperse the convoy under pressure from Washington.

So grave is the fallout from the disappearance of Saudi journalist Jamal Khashoggi that King Salman has felt compelled to intervene, five sources with links to the Saudi royal family said.

US Defense Secretary Jim Mattis and his South Korean counterpart Jeong Kyeong-doo have canceled the "Vigilant Ace" military exercise that was slated for December, a Pentagon spokeswoman said Friday.

US President Donald Trump threatened on Tuesday to withdraw funding and aid from Honduras if it does not stop a caravan of people that is heading to the United States, in his latest effort to show his administration's tough stance on immigration.

North Korea's foreign minister on Saturday told the United Nations there was "no way" that his country would disarm first as long as the United States continued to push for tough enforcement of sanctions against Pyongyang.

The United States announced a 185-million-dollar boost in aid to Rohingya refugees late Monday.

"The United States condemns any terrorist attack anywhere, period. We've always stood by that," Nikki Haley, the US ambassador to the United Nations, told CNN.

Iranian Foreign Minister Mohammad Javad Zarif blamed "a foreign regime" backed by the United States for Saturday's attack on a military parade which killed at least eight troops and several civilians.

On Thursday, the United States expanded its sanctions war against Russia to China, for the first time announcing punitive measures against a Chinese military organisation for buying Russian fighter jets and missiles.

The United States is seeking to negotiate a treaty with Iran that will cover both its ballistic missile and nuclear programs, US special envoy for Iran Brian Hook said on Wednesday ahead of UN meetings in New York next week.