North Korea likened US President Donald Trump to Adolf Hitler on Tuesday in its latest diatribe amid high tensions over Pyongyang's military ambitions and ahead of a visit to Washington by the South's new leader.

Khalid, a 13-year-old from Afghanistan, spends his days in squalor repeatedly trying to scale a metal fence separating him from the better life he dreams about at night.

The Mexican attorney general's office said it would ask the US Federal Bureau of Investigation for help probing allegations that the government spied on journalists and activists.

The United States urged China on Tuesday to give cancer-stricken Nobel peace prize laureate Liu Xiaobo and his wife freedom to move and choose his own doctors after he was granted medical parole.

Syrian President Bashar al-Assad may be preparing a chemical weapons attack that would result in the "mass murder" of civilians, the White House said Monday, warning the regime would pay a "heavy price" if it goes ahead.

The United States on Tuesday urged China to grant Nobel laureate Liu Xiaobo and his wife "freedom of movement" and let him choose his own doctors after the cancer-stricken activist was taken from prison to a hospital.

If, however, Mr. Assad conducts another mass murder attack using chemical weapons, he and his military will pay a heavy price," the White House statement read.

On Saturday, 198 of the world's best cyclists will start the Tour de France. Only four have a realistic shot at winning.

The story relied on only one source who made claims that were refuted almost immediately after the story was published.

"The CBO has consistently proven it cannot accurately predict how healthcare legislation will impact insurance coverage," the White House said.

The former vice president is still fiery as ever.