Zelensky will discuss the grain deal with the Turkish president, also with a NATO bid in mind.

Ukraine’s President Volodymyr Zelensky caps off an intense week of diplomacy with a visit to Istanbul on Friday to meet with the Turkish president over the Black Sea grain deal that faces yet another uncertain future, according to Turkey’s state news agency Anadolu.

Turkey and the United Nations signed an agreement last year to allow Ukrainian grain to be exported through Russia’s Black Sea blockade. Moscow has repeatedly threatened to cancel the contract, saying it hampers Russia’s own exports, but last-minute extensions have kept the deal alive so far. An extension agreed in May ends July 17.

Mr Zelensky and President Recep Tayyip Erdogan will meet amid renewed pressure on Mr Erdogan to approve Sweden’s bid to join NATO. Mr Erdogan has blocked Sweden’s membership for months, accusing the country of harboring dissidents considered terrorists by Turkey. NATO officials, who hope the issue will be resolved at an annual summit next week in Vilnius, Lithuania, cause a failure to move forward expanding the alliance would be a symbolic victory for President Vladimir V. Putin of Russia.

Kremlin spokesman Dmitry S. Peskov said Friday that Russia will closely monitor the outcome of the meeting. Mr Peskov added that Russia considers Turkey an important partner and “deeply values” its relationship with Mr Erdogan.

Ukraine’s own application for membership in the North Atlantic Treaty Organization will be an open question at the two-day summit, which President Biden will attend. The meeting on Tuesday and Wednesday is intended to demonstrate transatlantic unity and solidarity support for Ukraine while fighting the invasion of Russia. Mr Zelensky has said he expects the alliance to invite Ukraine to the event, even if his country cannot become a full member until after the war.

In an interview with CNN broadcast on Wednesday night, Mr Zelensky said he wanted Mr Biden to invite Ukraine to NATO now, saying the US president was “the decision maker” on whether Ukraine would be in the alliance.

“He supports our future in NATO,” Zelensky said in the interview, but an invitation now would be a huge motivator for Ukrainian soldiers.

In the meantime, Mr. Zelensky has made the issue a central part of his most recent diplomatic tour. On Thursday he was in Bulgaria to discuss military and energy cooperation. While there, the NATO nation’s parliament passed a statement of support for Ukraine’s membership.

Later in the afternoon, Mr. Zelensky to Prague, where he met President Petr Pavel and said that by supporting Ukraine’s hopes of joining NATO and the European Union, the Czech Republic helped “bring victory closer”.

Steven Erlanger reporting contributed.