The U.S. decision not to participate in an annual Turkish military exercise is raising questions about ties between the two NATO allies. Those ties have been tested by the rapid deterioration in relations between Turkey and Israel and Ankara's decision to vote against U.N. sanctions against Iran earlier this year.
When U.S. Joint Chiefs of Staff Chairman Admiral Michael Mullen visited his Turkish counterpart General Isik Kosaner last weekend in Ankara, he put a positive spin on relations between their countries in the past two years.
"Certainly much has changed since then, not least the end of the American combat mission in Iraq and the surge in Afghanistan," Mullen said. "Two missions for which, and in which, Turkey's assistance has been vital."
But the United States will not use Turkey, which neighbors Iraq, in withdrawing combat troops and weapons, although Ankara has said it will look favorably on a request to help in the withdrawal of non-combat personnel and non-military vehicles.
Diplomatic correspondent Semih Idiz says the strategic relationship between Turkey and the United States now exists only in name. "We are dealing with a case by case account here, rather than the global strategic relationship, which [they] may of had in the past," Idiz states. "So under a strategic relationship you can take certain things for granted. But under the present circumstances there is no situation where either country can take anything for granted and will probably have to work as each case arises."
The Islamic-rooted Turkish government's assertive foreign policy role is most visible in its relations with Israel.
Bilateral relations between the two U.S. allies have collapsed over the plight of Palestinians living in Gaza, culminating in Turkish anger at the killing of nine Turks by Israeli forces during an operation to stop ships trying to break a blockade of Gaza.
The fiery rhetoric of Turkish Prime Minister Recep Tayyip Erdogan accusing Israel of terrorism has caused questions in Washington over the direction of Turkish foreign policy. Those questions have grown following Turkey's vote against new U.N. sanctions on Iran, says international relations expert Soli Ozel.
"Not only we defy our partners, we are extraordinarily reluctant to work with them or to be on the same page as them," Ozel said.
Turkey has said it will enforce the new U.N. sanctions, but not new U.S. or E.U. measures against Iran.
Last month, a high-level delegation of Turkish diplomats was dispatched to Washington to ease tensions. Meeting with their counterparts and key U.S. lawmakers, the delegation stressed its belief in the value of good long-term Turkish-Israeli relations.
Ambassador Selim Yenel says the visit was a success in rebuilding relations. "Having face-to-face talks was something good and something was needed. But we also made emphasis on those areas that do not make headlines - unfortunately the positive aspects of our relationship, which is we see eye-to-eye on Iraq, Afghanistan, Pakistan, the Balkans, we are working consistently together on all these issues," Yenel said.
Analysts say Turkish cooperation in Afghanistan is of particular importance to the United States. Turkish forces are playing a lead role in training Afghan soldiers and police, and being the only Muslim member of NATO there also carries a powerful symbolic value.
But Ambassador Yenel says problems remain in particular with the U.S. Congress, which is deliberating the sale of weapons to Turkey.
"Right now, people have a difficult image of what is going on in our region, and they have a slightly negative view with the regard to Turkish action. I think if we go there and address them and talk to them, and explain the real situation, this might help Congress pass these. But right now the position is not so positive," Yenel said.
Turkey says the weapons are key to its fight against a Kurdish rebel insurgency that has markedly increased in the past few months, claiming the lives of more than 100 Turkish soldiers.
Columnist Idiz says if Congress rejects the weapons sale it will have far-reaching consequences for bilateral relations. "That will feed back on the anti-Americanism we have in Turkey and this action-and-reaction situation, which will lead to an escalation that diplomats cannot avoid," Idiz said.
With a general election due in less than a year in Turkey, the importance of public opinion will grow. Meanwhile, Ankara is expected to face further hard choices over Iran, as E.U. and U.S. pressure is likely to grow.