Russian PM Vladimir Putin has praised Leonardo DiCaprio as "a real man" for his persistence in getting to a St Petersburg summit on saving tigers.
His first plane was forced to make an emergency landing after losing an engine, while a second had to stop after encountering strong headwinds."I would like to thank you for coming despite all the obstacles," Mr Putin told DiCaprio at the conference.
DiCaprio has pledged $1m (£635,000) to the effort.
Mr Putin broke off from a prepared speech after he spotted DiCaprio in the audience."A person with less stable nerves could have decided against coming, could have read it as a sign - that it was not worth going," Mr Putin said.
The prime minister said that, in Russia, DiCaprio's efforts made him a "muzhik" - or "real man".
Russian roots A Delta Airline plane DiCaprio was travelling in on Monday was forced to make an emergency landing.
A second plane was forced to make an unscheduled refuelling stop in Helsinki.
DiCaprio told the prime minister that two of his late grandparents were Russian, and that he had always wanted to take his grandmother to St Petersburg.
"I'm sure when you get to know St Petersburg you will be proud of your Russian roots," Mr Putin said.
Governments of 13 countries where tigers still live met in Russia on Tuesday for the summit to discuss a plan to save the big cats from extinction.
In the last 100 years, tiger numbers have dropped from about 100,000 to less than 3,500 tigers in the wild today.
Delegates agreed to double tiger numbers by 2022, to focus on protecting tiger habitats and to address poaching.