HELSINKI—The Pentagon’s top officer met with his Russian counterpart in the Finnish capital Wednesday amid American and allied efforts to find ways to fight terrorism after the departure of U.S. and allied troops from Afghanistan last month.

Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley met here with Chief of Russian General Staff Gen. Valery Gerasimov, officials said. U.S. military officials declined to provide any details of the meeting, except to issue a brief statement saying the two discussed “risk reduction...

HELSINKI—The Pentagon’s top officer met with his Russian counterpart in the Finnish capital Wednesday amid American and allied efforts to find ways to fight terrorism after the departure of U.S. and allied troops from Afghanistan last month.

Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley met here with Chief of Russian General Staff Gen. Valery Gerasimov, officials said. U.S. military officials declined to provide any details of the meeting, except to issue a brief statement saying the two discussed “risk reduction and operational de-confliction.”

The U.S. and Russia have in the past discussed how to avoid conflict in Syria, where both countries maintain troops, and in the Black Sea, where both militaries conduct naval patrols. The two sides have also discussed Moscow’s incursion into Crimea and its massing of forces along Ukraine’s eastern and southern borders.

But Gen. Milley, on a tour through Europe this week, has been focused on terrorism and countering violent extremism in the region. He met NATO chiefs of defense in Athens before meeting with a smaller group of his counterparts in Berlin on Monday. On Tuesday, he was in London meeting with the military chiefs of the so-called Five Eyes nations, including Canada, Australia, the U.K. and New Zealand.

The meeting with Gen. Gerasimov comes weeks after the tumultuous end to the U.S.’s 20-year presence in Afghanistan, with the Taliban quickly assuming power once again and the U.S. limited in its ability to keep a lid on terrorism emanating from inside the country.

President Biden has said the U.S. will remain vigilant to ensure that militant groups like al Qaeda or the Afghanistan branch of Islamic State don’t reconstitute to the point that they can threaten Americans at home or abroad. Mr. Biden, along with top military officials like Gen. Milley, have said the U.S. can monitor the situation on the ground and conduct airstrikes as needed to keep militant groups at bay.

But that so-called “over the horizon” capability means drones or manned aircraft must fly hundreds of miles from bases in the Gulf region, depriving the U.S. military of adequate coverage of landlocked Afghanistan. When Mr. Biden announced his decision to withdraw from Afghanistan in April, U.S. officials said they hoped to establish a presence nearby in Central Asia, possibly in Uzbekistan, to help conduct counterterrorism operations from there.

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So far, however, the Russian government has been unwilling to support the American endeavor. Russian President Vladimir Putin rejected Mr. Biden’s entreaties for such a base at a summit in Geneva in June.

On Wednesday, the U.K. is expected to call for China and Russia to agree to an international plan to prevent Afghanistan from becoming a haven for militants, according to a statement from British Foreign Secretary Liz Truss, at the United Nations General Assembly in New York.

The Helsinki meeting between Gens. Milley and Gerasimov was the second time the two met in person, having previously met in December 2019 in Switzerland. The two have had several conversations since Gen. Milley took office in September 2019.

Write to Gordon Lubold at Gordon.Lubold@wsj.com