The countries have long worried about being sucked into regional war as they juggle relations with Washington, their security guarantor, while seeking to improve ties with Tehran.

Iran launched retaliatory strikes Qatar's Al-Udeid airbase, a critical U.S. military hub for CENTCOM operations, following American attacks on Iranian nuclear sites.

By Andrew Mills, Parisa Hafezi and Alexander Cornwell DOHA/ISTANBUL/TEL AVIV (Reuters) -Iran launched a missile attack on an American air base in Qatar on Monday that caused no injuries, and U.S. President Donald Trump dismissed it as a "weak response" to U.