Axios

In a letter released Sunday, a group of Senate Democrats demanded that President Trump provide "tangible, verifiable progress on denuclearization" from his second summit this week with North Korean leader Kim Jong-un in Vietnam.

Details: The eight lawmakers, including Senate Minority Leader Chuck Schumer, acknowledged that Kim has shown a "change in behavior" since the two leaders first met in Singapore last year, but said the isolated country still poses a nuclear threat and argued that Trump should "execute a serious diplomatic plan," including a process to verifiably freeze and roll back North Korea's nuclear weapons and missiles programs.

Go deeper: Trump team unsure if North Korea is serious about denuclearization

Secretary of State Mike Pompeo told "Fox News Sunday" that "there may have to be another summit" after President Trump's upcoming meeting in Vietnam with North Korean leader Kim Jong-un — as it may not accomplish all of Trump's goals.

The big picture: During another appearance on CNN's "State of the Union," Pompeo told Jake Tapper that North Korea remains a nuclear threat, despite Trump's claim to the contrary immediately after his first summit with Kim last year in Singapore.

Special counsel Robert Mueller has filed a sentencing memo for President Trump's former campaign manager Paul Manafort. Mueller does not take a position on how much time in prison Manafort should serve, but accuses him of "repeatedly and brazenly" breaking the law for over a decade, even after he was indicted.

"Based on his relevant sentencing conduct, Manafort presents many aggravating sentencing factors and no warranted mitigating factors."

Why it matters: Already, the 69-year-old Manafort faces a potential sentence of 19 to 24 years in his Virginia financial fraud case. The sentencing memo for Manafort's D.C. case, which is more than 800 pages with attachments, relates to his lobbying on behalf of Ukraine and could play a significant role in Mueller's broader investigation into ties between the Trump campaign and Russia.

Saudi Crown Prince Mohammad bin Salman, who is currently in Beijing to sign billion-dollar economic partnerships with China, said on Friday: "China has the right to carry out anti-terrorism and de-extremization work for its national security," referencing the detention of 1 million Uighur Muslims in "re-education camps," reports the Telegraph.

The big picure: Many Western countries have called for Chinese President Xi Jinping to end the mass detention of Uighurs, with the U.S. reportedly considering sanctions under the Magnitsky Act against senior Chinese officials involved in the crackdown. Turkey has also condemned China for its treatment of Uighur Muslims, one of the first Muslim-majority countries to do so.

Go deeper: U.S. firm aided Chinese DNA collection of Uighur Muslims

In a new paper, a senior European Union economist suggests anew that the political upheaval on both sides of the Atlantic could erupt into World War III, a danger that numerous scholars and politicians have flagged for a couple of years.

Details: In his paper, however, Gerhard Hanappi, a professor at the Institute for Mathematical Models in Economics at the Vienna University of Technology, describes how such a war could unfold: Between the U.S., Russia and China; in the form of multiple, small civil wars within countries; between poorer and richer nations of the world.