Donald Trump has picked Rex Tillerson, the CEO of oil and gas multinational ExxonMobil, to be his Secretary of State.

Mr Tillerson, 64, has attracted significant criticism from Republicans for his apparent ties to Russian President Vladimir Putin.

His company has billions of dollars in oil contracts with Russia that can only go forward if the US lifts its sanctions against the country, The New York Times reports.

While the Texan has ample experience dealing with other nations, he has worked strictly as a businessman, not a diplomat.

"I have chosen one of the truly great business leaders of the world, Rex Tillerson, Chairman and CEO of ExxonMobil, to be Secretary of State," the President-elect announced on Twitter.

"The thing I like best about Rex Tillerson is that he has vast experience at dealing successfully with all types of foreign governments," he added.

Diplomatic experience

Mr Tillerson's diplomatic experience stems from the deals he made with foreign countries as the head of the world's largest energy company, ExxonMobil.

He is known for his Russian connections and represents Mr Trump's most concrete outreach yet to Mr Putin.

World reaction to President Trump: In pictures Show all 29 1 /29 World reaction to President Trump: In pictures World reaction to President Trump: In pictures London, England AP World reaction to President Trump: In pictures London, England Reuters World reaction to President Trump: In pictures Manila, Philippines Getty Images World reaction to President Trump: In pictures Manila, Philippines Getty World reaction to President Trump: In pictures Mosul , Iraq Getty World reaction to President Trump: In pictures Manila, Philippines AP World reaction to President Trump: In pictures New Delhi, India Reuters World reaction to President Trump: In pictures Karachi, Pakistan EPA World reaction to President Trump: In pictures Jakarta, Indonesia Reuters World reaction to President Trump: In pictures Lagos, Nigeria AP World reaction to President Trump: In pictures Kabul, Afghanistan AP World reaction to President Trump: In pictures Jerusalem. Israel Reuters World reaction to President Trump: In pictures Moscow, Russia Reuters World reaction to President Trump: In pictures Seoul, South Korea AP World reaction to President Trump: In pictures Lagos, Nigeria AP World reaction to President Trump: In pictures Peshawar, Pakistan EPA World reaction to President Trump: In pictures Jakarta, Indonesia Reuters World reaction to President Trump: In pictures Hyderabad, India AP World reaction to President Trump: In pictures Kolkata, India AP World reaction to President Trump: In pictures Sydney, Australia Getty World reaction to President Trump: In pictures Sydney, Australia AP World reaction to President Trump: In pictures Aleppo, Syria Reuters World reaction to President Trump: In pictures Mexico City, Mexico AP World reaction to President Trump: In pictures Port-of-Spain, Trinidad and Tobago Reuters World reaction to President Trump: In pictures Jerusalem, Israel EPA World reaction to President Trump: In pictures Baghdad, Iraq Rex World reaction to President Trump: In pictures Gaza Strip, Palestinian Territories Rex World reaction to President Trump: In pictures Tokyo, Japan Rex World reaction to President Trump: In pictures Mexico City, Mexico Getty

In 2011, he negotiated an energy partnership with Russia believed to be valued at approximately $500bn (£394bn), The Wall Street Journal reported.

A year later, the Kremlin awarded him the Order of Friendship, the country's highest honour for foreign nationals.

"My relationship with Vladimir Putin, which dates back almost 15 years now, I've known him since 1999 and have a very close relationship with him," Mr Tillerson said in a speech a few years ago, at the University of Texas-Austin.

Donald Trump brands Russian hacking claims 'ridiculous'

He has previously argued against sanctions placed on Russia by the US and its European allies after it annexed the Crimean Peninsula from Ukraine in 2014 and could work to lift sanctions in his role as the top US diplomat.

Foreign policy challenges

Mr Tillerson has also backed free trade and an expansive US presence in the Middle East, which puts him at odds with the more isolationist approach Mr Trump has pitched.

He will face immediate challenges in Syria, where the country's nearly six-year civil war rages on, and in China, where Mr Trump has suggested he will take a more aggressive approach to deals.

Stance on climate change

Mr Tillerson also differs with Mr Trump on climate change. While he led ExxonMobil, he expressed his support for the Paris climate agreement, in which countries around the globe vowed to cut their carbon emissions.

Mr Trump has said he will back away from the agreement.

Mr Tillerson has also acknowledged the existence of climate change and stated the importance of addressing it.

"We believe that addressing the risk of climate change is a global issue," he said in May, during a company shareholder meeting.

Mr Tillerson said he was "honoured" by his selection and shares Mr Trump's "vision for restoring the credibility of the United States' foreign relations and advancing our country's national security."