The number of novel coronavirus cases in South Korea, Italy and Iran jumped on Sunday as infections in mainland China continued to grow, the latest figures show.

The big picture: As South Korea and Italy stepped up emergency measures amid rising case numbers, World Health Organization officials expressed concern about infections with no clear link to China. COVID-19 has killed at least 2,619 people and infected almost 80,000 others, with all but 27 deaths occurring in mainland China.

Democratic presidential candidate Sen. Bernie Sanders announced on CBS' "60 Minutes" Sunday a new plan to guarantee free child care and pre-kindergarten to all American children from infancy to age four.

Details: In the wide-ranging interview, Sanders told Anderson Cooper he planned to pay for universal childcare with a wealth tax. "It's taxes on billionaires," he said.

Former Vice President Joe Biden secured second place in the Nevada Democratic caucuses with former Southbend Mayor Pete Buttigieg third, according to NBC News projections Sunday.

Why it matters: It's a boost for Biden, who's widely tipped to be endorsed by House Majority Whip Jim Clyburn (D-S.C.) on Wednesday, ahead of this week's South Carolina primary.

The federal judge who sentenced President Trump's longtime adviser Roger Stone said his legal team provided no "factual or legal support" that would disqualify her from the case as she rejected the request Sunday.

Why it matters: U.S. District Judge Amy Berman Jackson, who sentenced Stone to 4o months in prison last week for crimes including obstruction of justice, lying to Congress and witness tampering, is considering his request for a new trial amid allegations of juror bias. But she dismissed suggestions she should be removed, saying the "pleading appears to be nothing more than an attempt to use the Court's docket to disseminate a statement for public consumption that has the words 'judge' and 'biased' in it."

Read the court order:

Go deeper: Nearly half of Republicans support pardoning Roger Stone

The Big Tent Project, a Democratic political group focused on promoting moderate presidential candidates, has sent hundreds of thousands of mailers bashing Bernie Sanders to black voters in South Carolina who voted in the state's 2016 primary.

Why it matters: Sanders' rise to the top of the pack, as dueling moderate candidates split their side of the vote, is worrying many in the Democratic political establishment who fear a socialist can't beat President Trump.

Over the past year, President Trump has told senior administration officials, including Attorney General Bill Barr, that he wants a major overhaul of national security surveillance powers and the secret court that approves them.

Behind the scenes: In one such discussion last year about the need to reauthorize government authorities to surveil U.S. citizens, Trump went so far as to say he'd rather get rid of the Foreign Intelligence Surveillance Act (FISA) altogether.

Effective Monday, the U.S. will begin blocking more foreigners from obtaining green cards and some visas based on the Trump administration's guesses about what kind of people they'll become and whether they may ever burden taxpayers.

Why it matters: The long-expected "public charge" rule effectively creates a wealth and health test, which could keep hundreds of thousands of people from making the U.S. their legal home.

The Transportation Security Administration (TSA) said Sunday that it is banning employees from using the Chinese-owned app TikTok for social media outreach, after Senate Minority Leader Chuck Schumer sent the agency a letter raising security concerns, AP reports.

The big picture: Schumer had previously requested that the U.S. government investigate whether TikTok poses any "national security risks. The app already has more than 110 million downloads in the U.S. alone, and it could become a Chinese vacuum for coveted American data as tensions between the countries continue to escalate.

Sen. Bernie Sanders won so big in the Nevada caucuses that Democrats are hard-pressed to sketch a way he's not their nominee.

Driving the news: With 60% of precincts counted (slow, but better than Iowa!), Sanders is running away with 46% of delegates — crushing Joe Biden's 20%, Pete Buttigieg's 15%, Sen. Elizabeth Warren's 10% and Sen. Amy Klobuchar's 5%.

Pete Buttigieg's campaign wrote a letter on Sunday asking the Nevada State Democratic Party to release early vote and in-person vote totals by precinct and address certain caucus errors identified by campaigns, The Nevada Independent reports.

The big picture: The campaign alleges that the process of integrating early votes on caucus day was “plagued with errors and inconsistencies,” and says it received more than 200 incident reports from precincts around the state.

Sen. Elizabeth Warren surged to 19% and second place in a CBS News/YouGov national poll released Sunday, trailing front-runner Sen. Bernie Sanders (28%) but edging out Joe Biden (17%) and Michael Bloomberg (13%).

Why it matters: The poll notes that only 42% of Democratic primary voters have made up their minds. While Warren underperformed in the first three states, her strong debate performance in Nevada last week may have given her campaign new life.

Marc Short, chief of staff to Vice President Mike Pence, claimed on "Fox News Sunday" that the White House has not received intelligence that Russia is seeking to help President Trump win re-election, calling it "false information" that has been selectively leaked by Democrats on the House Intelligence Committee.

The big picture: Short and national security adviser Robert O'Brien both dismissed reports published in the Washington Post and New York Times last week about a briefing provided by top election security official Shelby Pierson, an aide to outgoing acting director of national intelligence Joseph Maguire.

House Majority Whip Jim Clyburn (D-S.C.) said on ABC's "This Week" Sunday that Sen. Bernie Sanders' identification as a democratic socialist may be an "extra burden" in down-ballot House races if he were to win the Democratic nomination.

Why it matters: Clyburn's comments echo fears from many establishment Democrats, who worry the House majority they won in 2018 by taking moderate seats carried by President Trump could be at risk with Sanders at the top of the ticket.

White House national security adviser Robert O'Brien repeatedly rejected on ABC's "This Week" an assessment from a congressional briefing led by the Office of the Director of National Intelligence that Russia is interfering in the 2020 election to help President Trump get re-elected.

Why it matters: The report put the Trump administration under fresh scrutiny in regard to steps it has been taking to combat the kind of interference that the U.S. encountered in 2016.

Iranian state TV announced Sunday that hardliners won a landslide victory in the country's parliamentary elections two days ago, including all 30 seats in Tehran, AP reports.

Why it matters: Voter turnout in the election reached only 42.57%, according to Iran's Interior Ministry, the first time turnout dipped below 50% since the 1979 Islamic Revolution. The low turnout may signal dissatisfaction with the Iranian government and the election system.

About 150 prescription drugs — including antibiotics, generics and some branded drugs without alternatives — are at risk of shortage if the coronavirus outbreak in China worsens, according to two sources familiar with a list of at-risk drugs compiled by the Food and Drug Administration.

Why it matters: China is a huge supplier of the ingredients used to make drugs that are sold in the U.S. If the virus decreases China's production capability, Americans who rely on the drugs made from these ingredients could be in trouble.

Sen. Bernie Sanders is projected to handily win the Nevada Democratic caucuses, becoming the clear front-runner among 2020 Democratic presidential primary election candidates.

Why it matters: Nevada is the first state with a diverse population to hold a nominating contest, highlighting candidates' abilities to connect with voters of color — particularly Latino voters.

Michael Bloomberg, Bernie Sanders and Joe Biden — all close to 80 — are pushing the boundaries on social media, while their younger Democratic presidential rivals are comparatively staying out of the fray.

The big picture: President Trump's unexpected rise to political power has shown Democrats and world leaders the power of harnessing popular internet culture to get elected.

Antarctica's Eagle Island now has a side that's almost ice-free following this month's searing heat wave in the region, images released by NASA show.

Why it matters: "The warm spell caused widespread melting on nearby glaciers," NASA said in its report. It's the third major melt event of the 2019–2020 Southern Hemisphere summer, following warm spells in January and last November, according to the United Nation's World Meteorological Organization (WMO).