The warning, from Iran's president, followed days of heavy clashes over the disputed Nagorno-Karabakh region. [https://www.bbc.co.uk/news/world-europe-54449401?at_custom1=%5Bpost+type%5D&at_campaign=64&at_custom3=BBC+News&at_medium=custom7&at_custom2=facebook_page&at_custom4=9B645248-08A7-11EB-A582-023C3A982C1E](https://www.bbc.co.uk/news/world-europe-54449401?at_custom1=%5Bpost+type%5D&at_campaign=64&at_custom3=BBC+News&at_medium=custom7&at_custom2=facebook_page&at_custom4=9B645248-08A7-11EB-A582-023C3A982C1E)