Direct nuclear negotiations between the Trump administration and Iranian officials are expected to advance to a more technical level during the next round of talks slated to be held in Oman on Saturday. But major questions are looming.

Here are a few, according to The Associated Press: Just how much enrichment by Iran would be comfortable for the United States? What about Tehran’s ballistic missile program, which Mr. Trump first cited in pulling America unilaterally out of the Obama-era nuclear accord in 2018? Which sanctions could be lifted and which would remain in place on Iran?

Iranian officials, meanwhile, blame Israel for trying to undermine the sudden advance of U.S.-Iran diplomacy. It remains to be seen whether Tehran will raise such concerns in meetings with Chinese officials ahead of the next round of talks. Iranian Foreign Minister Abbas Araghchi is slated to discuss the status of the talks during a visit to Beijing later this week.

Russia launched a wave glide bomb and Iranian-made Shahed drone attacks on Ukrainian cities overnight, marking a major offensive escalation less than 24 hours after a purported Easter ceasefire that had been unilaterally declared by Russian President Vladimir Putin.

In strikes coming ahead of a highly anticipated peace strategy meeting Wednesday of U.S., Ukrainian, British and French officials, Russian military forces battered the Ukrainian port city of Odessa. A top local official in the city said a residential building in a densely populated area, civilian infrastructure and an educational facility were hit.

The attacks come against a backdrop of frustration on the part of the Trump administration, which continues to push for substantive end-of-war talks between Russia and Ukraine. Mr. Trump said last week that negotiations were “coming to a head,” while Secretary of State Marco Rubio suggested the U.S. may back away from the push if talks don’t progress soon.

China’s military continued work on biological and toxin research with potential military applications in 2024 and is using artificial intelligence as part of the effort, according to the State Department’s annual arms compliance report.

The report also warns that Russia, North Korea and Iran are conducting research that raises concerns about their adherence to the Biological Weapons Convention, a 1972 arms treaty that bans developing and stockpiling deadly bioweapons.

On China, the report repeated concerns from last year regarding Beijing’s failure to disclose details about offensive biological arms that include weaponized ricin and botulinum toxins, as well as military agents for spreading anthrax, cholera, plague and tularemia.

Mr. Trump faces a “critical window” to secure American interests in Ukraine’s future, according to Michael Yurkovich, who writes that “while peace talks extend, one thing is crystal clear: America and its closest neighbor, Canada, must act now to prevent China from turning postwar Ukraine into its European beachhead.”

“When the dust settles in Ukraine, a once-in-a-generation opportunity awaits to rebuild a war-torn nation and to create a powerful ally that serves North American strategic and economic interests,” writes Mr. Yurkovich, president of Refraction Asset Management Ltd., a Calgary-based company. He has invested in Ukraine since 2016. “Mr. Trump, who built his reputation on making deals that put America first, can forge a powerful partnership with Canada that ensures Ukraine’s reconstruction benefits American and Canadian workers and businesses, not Chinese communists.”

“The stakes couldn’t be higher,” he writes. “China is waiting in the wings, ready to offer ‘aid’ that comes with strings attached. Beijing isn’t interested in Ukraine’s freedom. It wants Ukraine’s resources and a stronger foothold in Europe to challenge American and Canadian power.”

Stacie E. Goddard, a political science professor and associate provost at Wellesley College, writes in an assessment published Tuesday by Foreign Affairs magazine that “it should now be clear that Trump’s vision of the world is not one of great-power competition but of great-power collusion: a ‘concert’ system akin to the one that shaped Europe during the 19th century.”

“What Trump wants is a world managed by strongmen who work together — not always harmoniously but always purposefully — to impose a shared vision of order on the rest of the world,” according to Ms. Goddard, who writes that “if history sheds any light on Trump’s new approach, it is that things may end badly.”

• April 22 — FDD’s Air and Missile Defense Program Launch, Foundation for Defense of Democracies

• April 23 — Central and Eastern Europe Strategy Summit 2025, Hudson Institute

• April 23 — Sinocentrism and the U.S.-China-Russia Grand Strategic Triangle, Stimson Center

• April 28-May 1 — RSAC 2025, RSA Conference 

• April 29 — The Stakes of Sino-American AI Competition, Center for a New American Security

• April 29-May 1 — Modern Day Marine Convention

• April 30 — The Hill & Valley Forum

• April 30 — Robins Air Force Base Tech Expo, NCSI