As Turkey's economy and relations with the US continue to worsen, there is growing concern in the West that President Erdogan will turn to Russia for support.
On Tuesday President Erdogan said Turkey would boycott electronic goods from the United States, in response to Washington’s sanctions and raised tariffs.
A 45 percent slide in the lira currency this year has been exacerbated by the dispute with Washington, which has seen tensions over Syria compounded by a tug-of-war over two religious figures.
Russia has predicted that the role of the US dollar will decline, and says it is looking at the possibility of using national currencies to settle trade deals with Turkey, China and Iran.
How significant is the Russian foreign minister’s trip to Ankara?
Sergei Lavrov’s attendance at the ambassadors’ conference in the Turkish capital on Monday and Tuesday has been arranged far in advance. It is ostensibly aimed at paving the way for a four-way summit on Syria in September, also involving France and Germany.
However, in the light of Turkey’s rift with the US, all eyes are on potential developments in its partnership with Russia.
A statement by the Russian foreign ministry used standard diplomatic language to talk about growing trade and common interests between the two countries.
However, at a joint news conference with his Turkish counterpart, Lavrov attacked US sanctions against Ankara and Moscow – describing them as an illegitimate policy and a way for Washington to obtain an unfair competitive advantage in global trade.
How close are Russian-Turkish ties?
Turkey is not isolated in feeling the pinch from Washington: Russia is also under US sanctions.
Moscow has backed President Erdogan in urging countries to scale back their use of the US dollar. In Ankara, Lavrov said Moscow had been discussing for some time the possibility of using national currencies to settle bilateral trade deals with Turkey, China and Iran.
However, the impact on Russian-Turkish ties of a potential Turkish economic collapse is unpredictable.
The chances of orthodox corrective measures being taken to correct the lira’s slide – such as a rise in interest rates – are lessened by what many see as Erdogan’s nationalist policies and complete control over fiscal and economic policy.
What does this mean for NATO and the West?
Turkey confirmed last December that Ankara and Moscow had finalised a contract for Russia to supply a Russian S-400 long-range air and anti-missile defence system. If it materializes, it will be the first time a NATO member has deployed the S-400.
There are real questions over the impact on the western military alliance, should Turkey’s economic war with the US result in a decisive tilt by Ankara towards Moscow.
Turkey has traditionally seen as being a buffer – and a bridge – between a relatively stable Europe, and instability and conflict to the east, in Syria and beyond.
The country is seen as less important economically from a global perspective, than it is from a strategic and military point of view.
It borders many countries: Bulgaria and Greece in the EU, as well as Georgia, Iran, Iraq, Syria, Armenia and an autonomous enclave in Azerbaijan. Serious disruption in Turkey could have an impact far beyond its own frontiers.
How bad could this get?
A recent opinion piece by Recep Tayyip Erdogan in the New York Times listed a catalogue of complaints over US policy: on the 2016 attempted coup, American support for Kurdish groups, and the recent sanctions imposed over the detained US pastor Andrew Brunson.
The president’s frustrations seem to outweigh his recognition that Turkey and the US have been “strategic partners and NATO allies” for six decades. Instead, he says “the United States has repeatedly and consistently failed to understand and respect the Turkish people’s concerns”.
Turkey, Erdogan concludes, may need to “start looking for new friends and allies”. Such friends are widely seen as including such heavyweights as Russia and Iran.
Some analysts believe that Donald Trump’s policy towards certain adversaries may have the ironic effect of strengthening alliances involving Russia, Turkey, Iran and Syria – potentially creating a very different geopolitical picture in the future.