Since taking over as secretary of state earlier this year, John Kerry has thrown himself into his new job, tackling a host of thorny foreign policy disputes with vigor and a sense of purpose.

While the White House has been distracted by the botched Obamacare rollout, Kerry has been busy abroad.

Just this week, Kerry was in Paris trying to soothe French anger over new revelations about U.S. surveillance. He also reached out to Saudi Arabia to reassure the longtime U.S. ally that it remains a vital partner amid reports of rising tensions between Washington and Riyadh over Syria and U.S. talks with Iran.

Even though Kerry initially strongly supported a strike in Syria, he quickly pivoted to support President Obama's decision to pursue diplomatic efforts to disarm Damascus' chemical weapons stockpile. Inspectors are now on the ground in Syria, tracking down Bashar Assad's arsenal.

Kerry is also close to an Afghan security deal, is pushing ahead with Mideast peace talks and held an historic meeting with Iran's new foreign minister, Mohammed Javad Zarif, over Tehran's nuclear program.

Kerry's former Senate staff describes his approach to negotiation as “the big Kerry arm” — his tendency to use his six-foot-four stature and decades of foreign policy experience in the Senate to apply just the right amount of physical pressure in talks to achieve results.

Unlike his predecessor, Hillary Clinton, who had an eye on the 2016 presidential race throughout her tenure, Kerry is not inhibited by electoral politics and relishes one-on-one mediation in the world's most troubled hot spots.

Still, Kerry has his work cut out for him trying to bring coherence to what critics call Obama's zig-zag foreign policy.

A potentially game-changing shake-up is happening in America's relationships with some of its most longstanding allies.

For months, leaks of once-secret information about the National Security Agency's spying has outraged some of Washington's most important strategic U.S. partners. And over the weekend, Saudi Arabian officials distanced themselves from Washington and pulled back on cooperation with the U.S. on training Syrian rebels.

Riyadh also renounced its seat on the U.N. Security Council in what Prince Bandar Bin Sultan al-Saud reportedly told diplomats was a direct rebuke to the U.S. over its talks with Iran on Tehran’s nuclear program.

If Kerry, the former chairman of the Senate Foreign Relations Committee, has major disagreements with his commander-in-chief, he's playing the good soldier and not showing them.

The son of a career diplomat, Kerry will turn 70 in December and with a failed run for president already behind him, he seems focused on leaving behind a legacy as a secretary of state who produced results and didn't shy away from the biggest conflicts of his time.