Turkish Defense Minister Hulusi Akar met military officials on Thursday to discuss a possible offensive east of the Euphrates river in Syria as Ankara ramped up warnings of a cross-border operation. The meeting came a day after Turkey said it would launch an offensive unless agreement on a planned safe zone in Syria could be reached with the United States, saying it had run "out of patience" with Washington. The operation, which would mark the third Turkish incursion into Syria in as many years, was first signaled by President Tayyip Erdogan earlier this year but later put on hold. Following President Donald Trumps announcement of a planned US withdrawal from northern Syria, the two NATO allies agreed to create a zone inside Syria and along its northeastern border with Turkey that would be cleared of the Kurdish YPG. The YPG was Washingtons main ally on the ground in Syria during the battle against ISIS, but Turkey sees it as a terrorist organization. Ankara says that the United States has stalled progress on setting up the safe zone and has demanded that Washington sever its relations with the YPG. A US delegation led by special envoy for Syria James Jeffrey presented proposals this week which failed to satisfy Turkish officials, Foreign Minister Mevlut Cavusoglu said. On Thursday Akar told Turkish military officers that Ankara had set out its view to the US delegation. "We emphasized to them once again that we have no tolerance for any delays, and that we will use our initiative if necessary," the Defense Ministry quoted Akar as saying. Earlier on Thursday, Turkish military officials said that Ankara and Washington would continue to discuss the planned safe zone despite rising tensions between the allies. "We cannot share details as efforts are under way. Our aims are clear. The Turkish army is the only force capable of doing this," one of the officials said regarding the safe zone. He reiterated Turkeys frustration that an agreement reached a year ago with the United States to clear the northern Syrian town of Manbij of YPG fighters had not been implemented.