Arms control

Ahead of Mr. Pompeo’s trip, a senior State Department official told reporters that an arms control agreement would be at the top of the agenda.

In February, the Trump administration suspended a landmark nuclear arms-control pact, the Intermediate-Range Nuclear Forces Treaty, also known as the I.N.F., saying the United States would terminate the accord within six months if Russia did not come into compliance with the treaty. The next day, Mr. Putin responded that Russia would also suspend its obligations.

The treaty — signed in 1987 by President Ronald Reagan and Soviet leader Mikhail S. Gorbachev and seen as one of the most important nuclear agreements in history — limited the development and deployment of intermediate-range missiles designed to deliver nuclear warheads. It will come to an end this summer if no action is taken by either side. During the Obama administration, the United States concluded that Russia had been in violation of the treaty since at least 2014, though Moscow disputes that.

Analysts have long highlighted the limitations of the treaty, which did not take into account the development of the same weapons systems by other nations, including China. Earlier this month, President Trump said that in a phone call with Mr. Putin he had discussed the potential for a new, three-way deal on nuclear arms that would include China.

Renewed tensions with Iran

Since President Trump last year announced America’s withdrawal from the Iran nuclear deal, his administration has slowly reinstated punishing sanctions on Tehran. In recent weeks, Iran signaled it would reduce compliance with the restrictions imposed by the agreement unless the European parties to the deal provide Tehran with promised economic benefits. That seems unlikely, in that European companies refuse to do business with Iran for fear of the American sanctions.