MOSCOW—Russian President Vladimir Putin said his government would continue to deliver military assistance to the Syrian regime amid concerns over Moscow’s military buildup in the Middle Eastern country.

“We support the government of Syria in its effort to counter terrorist aggression,” Mr. Putin said Tuesday at a security summit in Dushanbe, the capital of the Central Asian republic of Tajikistan. “We provide and will continue to provide military assistance. We call on other countries to join with us,” he added.

Mr....