Iranian President Hassan Rouhani postponed a two-day visit to Austria indefinitely for security reasons on Tuesday (March 29), the evening he was supposed to arrive in Vienna, his Austrian counterpart’s office said.

It was not clear what the security reasons were, a spokeswoman for Austrian President Heinz Fischer’s office said.

A planned Rouhani visit to Baghdad immediately before the Austrian trip had, however, also been postponed for security reasons, Fischer’s office and an Iranian official said, Reuters reported.

“We were working (on preparations) until 5, 5:30 p.m.,” the spokeswoman said, underlining the short notice as Rouhani had originally been expected to arrive around 7:30 p.m. local time.

The visit was due to be Rouhani’s second to the European Union since international sanctions against his country were lifted in January under a landmark nuclear deal with major powers that was negotiated in Vienna last year.

Rouhani, the chief architect of the nuclear deal and keen to open Iran’s economy to the world, had been due to meet Fischer and other officials on Wednesday and Thursday.

Fischer issued a statement expressing regret and understanding at Rouhani’s move, without explaining it.

“Of course, it goes without saying that each state must make its own decisions about security and the head of state’s security,” Fischer said. “The quality of relations with Iran will not be affected by this postponement.”