Turkish President Tayyip Erdogan on Sunday said his government still intends to buy a second batch of S-400 missile defense systems from Russia, a move that could deepen a rift with Washington and trigger fresh U.S. sanctions.Washington says the S-400s pose a threat to its F-35 fighter jets and to NATO's broader defense systems. Turkey says it was unable to procure air defense systems from any NATO ally on satisfactory terms. Appearing on CBS’s “Face the Nation”, Erdogan said only Turkey can make decisions for itself. "In the future, nobody will be able to interfere in terms of what kind of defense systems we acquire, from which country at what level. Nobody can interfere with that. We are the only ones to make such decisions.” The U.S. imposed sanctions on Turkey's Defense Industry Directorate, its chief and three other employees in December following the country's acquisition of a first batch of S-400s. Talks continued between Russia and Turkey about the delivery of a second batch, which Washington has repeatedly said would almost certainly trigger new sanctions. Erdogan will meet with Russian President Vladimir Putin next week to discuss issues including the violence in northwestern Syria, with the two countries on opposing sides of decade-long civil war.Turkey on Sunday sent reinforcements to the last rebel-held enclave in the northwestern region of Syria, as Russia – which backs Syrian President Bashar al-Assad - stepped up air strikes in the region.