Belarus’s leader tries to play down suggestions that recent military moves were aimed at Ukraine.

President Aleksandr G. Lukashenko of Belarus, Russia’s closest ally, tried on Thursday to defuse suspicions in neighboring Ukraine that recent military moves inside his country could presage a new ground offensive aimed at the country.

Speaking a military conference, Mr. Lukashenko dismissed as “conspiracy theories” recent speculation from some Ukrainian officials that a suddenly announced check of combat readiness could be a precursor to a deployment Belarusian armed forces to assist Russia.

While insisting that the exercises, which also involved thousands of Russian troops, were limited to his country’s territory, he raised the possibility that Belarus could at some point be pulled into the fighting in Ukraine.

“If you want peace, prepare for war,” Mr. Lukashenko said. “We have been conducting exercises,” he added, referring to joint exercises with Russia that have scaled up in recent weeks in response to what the Belarusian leader described as the “current situation and threats.”

The comments came days after Vladimir V. Putin of Russia visited Belarus to strengthen ties with Mr. Lukashenko, raising fears among Ukraine and its Western allies that a new Russian ground offensive could aim again at Kyiv, about 55 miles south of the Belarusian border.

Mr. Lukashenko is a close ally of Mr. Putin, in part because Belarus depends on Moscow for fuel and security. And although Mr. Lukashenko has resisted being drawn more centrally into the war since February, when Russia used eastern Belarus as a staging ground for its full-scale invasion of Ukraine, he has come under increasing pressure from Moscow.

The Kremlin’s spokesman, Dmitri S. Peskov, this week dismissed speculations that Belarus would become directly involvemd in the conflict as “totally stupid” and “groundless fabrications.”

The Institute for the Study of War, a Washington-based research group, has said that Russia is unlikely to establish a fresh strike force in Belarus. It is more probable, the group has said, that the flurry of military activity is part of a broader effort to divert Kyiv’s troops from the front line in eastern and southern of Ukraine.

But intensifying pressure from Moscow is limiting Mr. Lukashenko’s “maneuver room to avoid making concessions to the Kremlin,” the institute said on Tuesday. It also said that Mr. Putin “gave” his ally an unspecified number of S-400 air defense systems during his visit to Minsk this week, a move that the Belarusian leader had rejected in recent years. The air defense systems will likely be operated by Russian troops based in Belarus, the group said.

“Lukashenko is likely delaying acceding to Putin’s larger demands — such as committing Belarusian forces to join the invasion against Ukraine — by making smaller concessions that he has stonewalled for years,” the group said.