DOHA, Sept 6 (Reuters) - U.S. Secretary of State Antony Blinken arrived in Qatar on Monday as Washington seeks support for the evacuation of Americans and at-risk Afghans left behind in Afghanistan and build a consensus among allies on how to respond to the Taliban. A senior State Department official told reporters on Blinken"s flight that Washington has facilitated the safe departure of four more Americans overland from Afghanistan. read more "This is the first overland evacuation facilitated by the State Department," the official said, adding that the Taliban were aware of the operation and did not impede safe passage of the individuals. The official did not name the country they transited to. Dubbed as a "thank you" tour to Qatar and Germany, which were instrumental in helping Washington evacuate thousands of people out of Kabul, Blinken will meet with senior Qatari and German officials. In Germany he will also co-host a ministerial meeting on Afghanistan. read more Qatar has emerged as the main mediator between the Taliban, who swept into Kabul on Aug. 15, and Western countries following the chaotic U.S. withdrawal from Afghanistan. Doha said on Saturday it had reopened Kabul airport for humanitarian aid and domestic flights in coordination with the hardline Islamist group. Other international flights are expected to resume soon, it said. Daily flights have been scheduled from Doha to Kabul to deliver aid. About 124,000 people were evacuated last month from Kabul in a U.S.-led airlift of U.S. and other foreign citizens as well as vulnerable Afghans as the Taliban took control of the country. The evacuation was one of the largest airlifts in history but thousands of at-risk Afghans and about 100 U.S. citizens have remained behind. Blinken has vowed to continue efforts to get them out and also hold the Taliban to their commitment to provide safe passage to anyone who wishes to leave. U.S. Defence Secretary Lloyd Austin, who is travelling to the Gulf on a separate trip, will also visit Qatar on Tuesday. Austin"s visit also includes Saudi Arabia and Kuwait.