Ukraine incursion — An apparent incursion of tanks and personnel carriers into southeastern Ukraine on Monday, one day before a high-stakes summit, demonstrated just how difficult it will be for Ukraine to re-establish control over its own territory. Even as Russian-backed separatists are losing ground on the battlefield, provocations launched from the Russian side of the two countries’ long border remain a constant threat. Monday’s column of military vehicles — which Moscow denied sending — appeared near the Sea of Azov, well to the south of the rebel-held city of Donetsk. It came just days after Russia sent a convoy of humanitarian aid trucks — whose purpose, even now, is murky — into Ukrainian territory, provoking international condemnation.

California nuclear plant — A senior federal nuclear expert is urging regulators to shut down California’s last operating nuclear plant until they can determine whether the facility’s twin reactors can withstand powerful shaking from any one of several nearby earthquake faults. Michael Peck, who for five years was Diablo Canyon’s lead on-site inspector, says in a 42-page, confidential report that the Nuclear Regulatory Commission is not applying the safety rules it set out for the plant’s operation. The document, which was obtained and verified by The Associated Press, does not say the plant itself is unsafe. Instead, according to Peck’s analysis, no one knows whether the facility’s key equipment can withstand strong shaking from those faults — the potential for which was realized decades after the facility was built.

Gaza conflict — Hundreds of Israelis left their homes along the border with the Gaza Strip on Monday, reflecting growing frustration over the war with Hamas and the Palestinian mortar fire raining down on their communities. Tens of thousands of Israelis have fled the area in nearly two months of fighting, which has turned the communities into virtual ghost towns. With the school year fast approaching, the government began offering assistance to residents Monday in the first large-scale voluntary evacuation in nearly eight weeks of fighting. Officials estimate that 70 percent of the 40,000 inhabitants of the farming communities along the Gaza border have left over the course of the fighting, including hundreds on Monday.

Strikes in Libya — Twice in the last seven days, Egypt and the United Arab Emirates have secretly launched airstrikes against Islamist-allied militias battling for control of Tripoli, Libya, four senior U.S. officials said, in a major escalation of a regional power struggle set off by Arab Spring revolts. The United States, the officials said, was caught by surprise: Egypt and the Emirates, both close allies and military partners, acted without informing the U.S. The strikes in Tripoli are another salvo in a power struggle defined by old-style Arab autocrats battling Islamist movements seeking to overturn the old order.

Vatican diplomat — The Vatican’s former ambassador to the Dominican Republic, who has been accused of paying underage boys there to engage in sexual acts, has lost his diplomatic immunity and could ultimately face prosecution in criminal courts outside the Vatican, a spokesman for the Roman Catholic Church announced Monday. The former ambassador, Archbishop Jozef Wesolowski, has already been defrocked, the harshest penalty under the church’s canon law short of excommunication. Beyond that, the Vatican has also said it intends to try Wesolowski on criminal charges — the first time it will hold a criminal trial for sexual abuse.

Perry indictment — Defense lawyers for Gov. Rick Perry of Texas on Monday sought to throw out a felony abuse-of-power case against him, calling it an unconstitutional prosecution that would set a dangerous precedent for future governors. The indictment, returned by a grand jury in Travis County, stems from Perry’s efforts to force the resignation of the county’s district attorney, Rosemary Lehmberg, after she was arrested on drunken-driving charges in April 2013. Perry is charged with threatening to veto funding to the office’s anti-corruption unit unless she quit, a threat he carried out with a veto that blocked $7.5 million in state money.

Grain backlog — The furious pace of energy exploration in North Dakota is creating a crisis for farmers whose grain shipments have been held up by a vast new movement of oil by rail, leading to millions of dollars in losses. The backlog is going to get worse, farmers said, as they prepared for an expected record crop of wheat and soybeans. Although the energy boom has led to the nation’s lowest unemployment rate, the downside has been harder times for farmers.