The silos are full and other storage almost at capacity. According to the Food and Agricultural Organization of the United Nations (FAO), 20 million tons of grain, originally destined for the global market, are currently stuck in Ukraine.

Ukraine used to ship over 50% of its exports from its largest Black Sea port in Odesa. But since the Russian invasion in late February, the loading cranes have stopped operating. A blockade by the Russian Black Sea fleet is preventing exports and imports. Moreover, all shipping is dangerous, as there are numerous sea mines along the Ukrainian coast, although it is hard to tell how many exactly.

What is certain is that Romania and Turkey have already detected and defused several potentially dangerous naval mines, which were adrift in the Black Sea after coming loose from their anchors.

Meanwhile, grain is urgently needed: There is a shortage of bread and other wheat products in several African and Middle Eastern states. And Ukraine is in desperate need of the revenues generated by grain exports. It has tried to export grain via rail in recent weeks, but this is a much slower process given that Ukrainian trains are not compatible with much of the European network rail because of differences in gauge widths, and there is also a lack of freight wagons. 

Sergey Lavrov in Ankara

Frantic attempts to relaunch exports via the Black Sea are currently underway and Russian Foreign Minister Sergey Lavrov traveled to Turkey this week to discuss the issue. "We are ready to ensure the safety of ships that leave Ukrainian ports," he told a press conference with his Turkish counterpart Mevlut Cavusoglu in Ankara on Wednesday. "We are ready to do this in cooperation with our Turkish colleagues," he added.

The idea is that a UN coordination body be set up in Istanbul to regulate how the grain is distributed across the world market.

Three Ukrainian ports are currently under consideration for loading the wheat: Apart from Odesa, Chornomorsk and Yuzhne are in question, but there is also talk of exporting the wheat from Mykolaiv, which is currently a battleground, or the ports of Kherson and Mariupol, which are under Russian occupation. 

In principle, Ukraine would be interested in such an agreement, but the government has a variety of reservations. Thus, the UN has proposed establishing a contact group with representatives from the UN, Turkey, Russia and Ukraine to create a control mechanism for a possible safe grain export corridor.

Beate Apelt, the head of the Turkey office of the Friedrich Naumann Foundation for Freedom, said that it would be possible "to establish such a corridor if everybody wants it." However, there are a number of sticking points, largely to do with the barriers of mines that both Russia and Ukraine have established along the coast. "The Ukrainian navy wants to prevent Russian warships from launching landing operations near Odesa," Apelt said.

It would be necessary to remove the mines so that freight ships transporting grain could pass, but Turkish experts calculate that this would be doable within one or two weeks. Yörük Isik from the Middle East Institute in Istanbul said that the Turkish navy was "one of the most experienced in NATO" for the task since it had at least 11 minesweepers and trained personnel.

Fear that Odesa could come under attack

However, if the mines were to be cleared, Odesa could be left without defenses and thus the Ukrainian government fears that Russian warships might use a safe corridor to attack Ukraine's largest port city. Kyiv is demanding security guarantees, such as Western anti-ship missiles, which the Russian government refuses to allow. "Given the monstrosities so far, I find it hard to imagine that Kyiv would believe a pledge of non-aggression from Moscow," said Apelt. "This is where Turkey comes into play. It not only wants to arbitrate the corridor but also secure it with its own ships."

The Turkish government has effectively declared its willingness to do this, but what remains doubtful is whether Kyiv would be satisfied with security provided only by Turkish ships. Yüsük Isik thinks that other states would have to put forward security guarantees for Ukraine to agree. For example, Turkey could work in cooperation with Britain and the US. However, even this safeguard would not be risk-free. So far, NATO has kept its own troops out of the conflict between Russia and Ukraine. If a protective convoy were to be attacked by either side, NATO warships could find themselves directly involved in fighting. This in turn could trigger an escalation of the war.

Who should benefit from grain revenues?

For its part, Russia insists on being allowed to inspect international freight ships before they enter a Ukrainian port. Otherwise, it fears, weapons for the Ukrainian army could enter the country. So far, Kyiv refuses to allow such inspections. Another bone of contention is how to distribute revenues from the grain, which will not only be exported from the greater Odesa area, but also from areas currently in Russian-occupied territory, such as Kherson and Mariupol.

Kyiv has already accused Russia of stealing grain from Ukrainian ports and exporting it, to Syria for example, but possibly also to Turkey. The Ukrainian embassy in Ankara has demanded that Turkey carry out stricter inspections of Russian ships in the Bosporus but so far to no avail.

There is some way to go before an agreement is met and it could well end up being painful for the West. "Moscow will presumably agree to a grain corridor only in return for the lifting of certain sanctions," predicts Apelt. At the press conference in Ankara, Turkish Foreign Minister Mevlut Cavusoglu hinted at possible concessions: "If we need to open up the international market to Ukrainian grain, we see the removal of obstacles standing in the way of Russia's exports as a legitimate demand."

"It is a difficult decision for Ukraine and its Western partners," said Apelt, adding that time was running out. According to the FAO, the world has about 10 weeks to find a solution. That is when its next wheat harvest is due to begin. Until then, the silos will have to be emptied.

Elmas Topcu contributed to this article, which has been translated from German.