Philippine President Rodrigo Duterte has lambasted the close ally United States for trying to hamper the modernization of his country’s army and for warning Manila against purchasing Russian submarines.

“Is that the way you treat an ally and you want us to stay with you for all time?  Who are you to warn us?” he said at an event in his hometown of Davao on Friday, addressing Washington, adding that if the Philippines purchased a submarine from the US, it would probably “implode, just like the helicopters” that it earlier bought.

Duterte further accused Washington of only supplying used military equipment to Manila, saying the US was providing the Southeast Asian country with NATO’s hand-me-down weapons systems.

The Philippine leader’s strong criticism came a day after US Assistant Defense Secretary for Asian and Pacific Security Affairs Randall Schriver warned Manila against buying Russian submarines.

“Why did you not stop the other countries in Asia? Why are you stopping us?” Duterte said, adding, “You want us to remain backwards. Vietnam has 7 submarines, Malaysia has 2, and Indonesia has 8. We alone don’t have one. You haven’t given us any.”

His comments come amid media reports that Moscow has purportedly offered the Philippine government its assistance in buying Russian Kilo-class diesel-electric submarines and that Manila is currently weighing the proposal.

The deal, in particular, stipulates the allocation of a subsidized loan to the Philippines, which would be paid back over several years.

Earlier this month, Philippine Foreign Minister Alan Peter Cayetano said at a meeting with his Russian counterpart Sergei Lavrov that Manila would not abandon the idea of purchasing Russian weapons even in the face of possible US sanctions against the country.

Furthermore, Duterte, during an official visit to Russia last year, expressed Manila’s interest in advanced Russian weapons, including helicopters, planes, as well as precision-guided weapons to help combat the threat of terrorism.