Islamic State of Iraq and Syria (ISIS) fighters have captured more than a third of the Syrian Kurdish town of Kobani, Reuters reports, citing the UK-based Syrian Observatory for Human Rights. But Kobani's slow-motion fall is being filmed by the media from across the nearby Turkish border, where Turkish tanks and infantry are also watching, doing nothing to intervene.

The U.S., which has conducted at least 19 airstrikes against ISIS forces outside Kobani, acknowledges that aerial bombardment won't roll back ISIS by itself. The White House wants Turkey, with NATO's second-largest army, to step in with ground forces, shelling, training Syria rebels, or at least letting Turkish Kurdish forces across to the border to help defend Kobani. But it's complicated.

First, Turkey is pretty open about wanting Syrian President Bashar al-Assad deposed, so sending troops into Syria is tricky. Second, Ankara has said it will only start fighting ISIS if the U.S. helps set up a humanitarian buffer zone in northern Syria, an idea Secretary of State John Kerry says is "worth looking at very, very closely," but is considered too expensive and knotty for U.S. planners.

Third, Turkish President Recep Tayyip Erdogan dislikes the Kurdish militias almost as much as ISIS. The Syrian Kurds fighting in Kobani, known as the YPG, are allied with Turkey's Kurdistan Worker's Party (PKK), a militant group engaged in a long battle for autonomy. "Americans officials fear Turkey could simply choose to remain out of the fray, and let two of its enemies — the Islamic State group and Kurdish guerrillas — fight for Kobani," says The Associated Press. "That would give the militants an opportunity to do as much damage to the Kurdish fighters in Syria as possible."

Turkish journalist Amberin Zaman is more direct. "Erdogan and his [ruling Justice and Development Party] AKP disciples view Kobani as an opportunity rather than a threat," she writes at Al Monitor.

Erdogan has chosen to exploit Kobani's imminent fall to wrest maximum concessions from assorted Kurdish leaders.... But Turkey would probably be happy to see Kobani fall.... Kobani's fall would deal a humiliating blow to the PKK and weaken its support among Syria's Kurds. [Al Monitor]

Retired U.S. Gen. John Allen, the U.S. envoy on ISIS, is in Ankara on Thursday to discuss the situation with Turkey. Peter Weber

Princess Charlotte, the daughter of Prince William and Kate Middleton, is set to turn 1 on Monday. What would a royal birthday be without some formal photos to celebrate? Kensington Palace shared a few gems of the tyke Sunday:

Nice camera work, Kate.

Could she be any cuter?

Time flies. Julie Kliegman

Democratic presidential hopeful Bernie Sanders raised $25.8 million in April, the campaign said Sunday. That's a sharp drop from the $44 million he pulled in in March.

The campaign put a positive spin on the news, noting it surpasses the campaign's monthly average of $17 million.

Hillary Clinton holds a large delegate lead over Sanders in the Democratic presidential race. In April, the struggling Sanders campaign announced layoffs of hundreds of staff members. Julie Kliegman

Malia Obama will attend Harvard University in 2017 after taking a gap year, President Obama and First Lady Michelle Obama announced Sunday. The decision to take a year off will theoretically lessen the spotlight in college, as her father will be out of office well before she starts classes.

Harvard's acceptance rate this year was just 5.2 percent, the lowest in the institution's history, The New York Times reports. Obama will join a storied club of presidential children that have attended Harvard as undergraduate or graduate students, which includes figures ranging from Robert Lincoln to George W. Bush. Julie Kliegman

In April, Democratic presidential frontrunner Hillary Clinton and New York City Mayor Bill de Blasio (D) made a seriously uncomfortable joke at a comedy show.

Here's a quick refresher: De Blasio, joking about his chronic lateness, said he was running on "CP Time." Colored People's Time has long been a reference to the racist stereotype that black people are frequently late. Clinton jumped in, jokingly claiming the acronym really means "Cautious Politician Time."

President Obama took Clinton and de Blasio to task Saturday during his speech at the White House Correspondents' Dinner. He apologized for being late and said he was running on CPT, which stands for "Jokes That White People Should Not Make." Watch the zinger below. Julie Kliegman

Rev. Daniel Berrigan, a Jesuit priest influential in forming U.S. opposition to the Vietnam War, died Saturday at age 94, The New York Times reports.

In 1968, Berrigan and his brother led other activists in seizing hundreds of local draft records in Catonsville, Maryland, and setting them on fire with homemade napalm. Berrigan was imprisoned. His activism and subsequent arrests continued in his later years.

"The day after I'm embalmed, that's when I'll give it up," he said in 2001. Julie Kliegman

Donald Trump leads the Republican presidential race in Indiana with 49 percent support among likely voters, according to a Wall Street Journal/NBC News/Marist poll out Sunday.

Ted Cruz sits 15 percentage points behind, with 34 percent support, and John Kasich notched just 13 percent. The margin of error is 3.9 percentage points.

On the Democratic side, Hillary Clinton holds a narrow lead over Bernie Sanders, 50 percent to 46 percent, ahead of Tuesday's primaries. That's smaller than the poll's 4.6-point margin of error. Julie Kliegman

Sen. Ted Cruz (R-Texas) picked up about 80 delegates of more than 170 on the table at local and state conventions Saturday, Politico reports.

He snagged a majority of delegates in Arizona and Virginia, two states that strongly backed Donald Trump in primaries. Cruz also made gains in Missouri. Trump fared well in Massachusetts, Alaska, and Arkansas.

Most delegates are obligated to support the winner of their state's nominating contest on the Republican National Convention's first ballot, but can switch allegiances in future rounds of voting. Cruz's strategy banks on Trump not being able to grab the minimum of 1,237 delegates needed to secure the party's nomination outright. Julie Kliegman