ISTANBUL (Reuters) - Recent developments in Syria s Raqqa show that the Kurdish YPG militia, backed by the United States, is more concerned about capturing territory than fighting Islamic State, Turkish Foreign Minister Mevlut Cavusoglu said in a speech on Thursday. Turkey has expressed anger that a convoy of Islamic State fighters were allowed to withdraw from Raqqa last month as part of an agreement with the YPG, saying it was  appalled  by the United States  stance on the issue. [nL8N1NK9RZ] Ankara was also infuriated by Washington s support for the Syria Kurdish fighters, seen by Turks as an extension of the outlawed Kurdistan Workers Party (PKK), which has fought a decades-long insurgency in Turkey and is designated a terrorist group by Ankara, the United States and European Union.  Turkish procurement of U.S. defence equipment is being delayed in the United States, according to the text of Cavusoglu s speech, and Turkey is developing alternative solutions for this sector.  We are unfortunately facing important delays in the procurement of defence equipment we urgently need in the fight against terror from the United States due to U.S. internal practices,  the text said, without elaborating.  Evidently, as these periods are prolonged, we are developing alternative means to acquire the equipment and systems we require, primarily through our own national resources.  Turkey recently completed the purchase of Russian S-400 surface-to-air missile systems, a defence deal that Turkey s Western allies see as a snub to the NATO alliance as the weapon cannot be integrated into the alliance s systems. [nL8N1NI0ED] Ankara also said it was making agreements with the Franco-Italian EUROSAM consortium to develop, produce and use its own sources for air defence system. [nL5N1NE7DI] 