The Navy secretary has spent more than a full year of his five-year tenure on overseas travel, racking up more than 930,000 miles on trips that cost the taxpayer more than $4.7 million.

Ray Mabus, the former Mississippi governor, has taken at least 40 trips outside the U.S as of July 2014, meeting officials and visiting sailors and Marines in more than 100 countries — travel he said is critical to his job in furthering U.S. and Navy interests abroad.

The inspector general investigated after receiving a complaint about his travel and cleared him of any wrongdoing, Mabus said, but his 373 days on the road contrast with those of Army Secretary John McHugh, who took fewer than half the trips at less than half the cost over the same time period.

According to data obtained and compiled by The Associated Press, Mabus' flights cost $4.6 million for fuel, maintenance and crew. Mabus also spent about $116,000 on hotels, meals and other costs. The Army leader's trips totaled 126 days and cost about $2 million for the flights. He spent under $33,000 for hotels, meals and other personal expenses on his 18 trips.

Mabus' entourage includes a security officer, military assistant, policy advisers and a public affairs officer — about seven people in all. Their per diem travel costs would approximate Mabus' and could add as much as $700,000 to the total costs of the travel. McHugh travels with up to 10 staff, so the per diem expenses could total more than $300,000.

The travel costs come amid deep budget cuts across the Defense Department, including widespread efforts to slash headquarters spending, downsize the Army and Marine Corps, and cut back on acquisition programs, training and other costs.

Those cuts, said Bryan Clark, senior fellow at the Center for Strategic and Budgetary Assessment, make it "even more important that senior leaders scrutinize their travel and make sure that the travel they're doing is essential."

Mabus is so proud of his travel he even has a mileage ticker on his Navy website, showing he has traveled 932,129 miles as of this week. Of the 325,000 sailors and nearly 190,000 Marines, as many as 100,000 are serving in nearly 100 countries around the world. And, he said, negotiating issues such as basing ships in Rota, Spain, is more effective face to face.

"You could do that in a phone call, I guess. You could send them a note," he said. "I don't think they take it nearly as seriously if you're not sitting across the table from them."

He noted that a female sailor on a stop in Hawaii complained to him that she felt she had no future as a nuclear officer because women couldn't serve on nuclear submarines. That conversation, said Mabus, led to his finalizing plans to allow women to serve on the subs.

"I think the return on investment for my travel has been phenomenal," Mabus told the AP. "In terms of the progress we've made with countries like Singapore, Spain, Gabon, Palau, Japan — in terms of advancing America's interests, in terms of advancing Navy interests, in terms of the work that we do together and the benefits that come from that — I think the return on investment has been huge."

Secretary McHugh oversees an Army of more than 508,000 active-duty soldiers, including more than 130,000 in over 150 countries.

He said he tries to go where large concentrations of soldiers are as well as countries where there are national security issues.

"I think a lot about the balance between the responsibilities of being here and the requirement to get out," McHugh said. "If someone were to ask me, have you traveled too little or too much — I'd say too little. I don't think you can ever be briefed in the Pentagon in a way that provides you an accurate perspective the way you can just seeing it on the ground for 10 minutes."

In May, McHugh stopped in Latvia, Estonia and Lithuania after a company of soldiers participated in military exercises last spring. He said he'd planned to visit only one of those countries, but the State Department advised him to visit all three.

According to data provided by the Army, McHugh has traveled to 29 countries, including seven visits to Germany, a frequent refueling and crew rest stop. He's been to Afghanistan four times and Iraq three times and he's made three visits to South Korea, where the Army has had a permanent presence since the Korean war.

Mabus had visited 107 countries as of July, including stops at major Navy homeports such as Singapore, Bahrain, Italy and Japan, as well as Africa, where piracy and terrorism have been persistent problems. He's also traveled to Greenland, Iceland and Norway — including a snowmobile safari on the tiny island of Svalbard.

The Arctic has become a key national security issue, as melting ice caps are opening up sea lanes and spurring competition for oil and gas deposits. The Navy is developing plans to increase communications, harden ships and negotiate international agreements so nations can better track traffic in the Arctic.

Mabus' most frequent destination — 12 stops — was Afghanistan, where thousands of Marines have served. But Spain is also a favorite with nine visits, including five times between May 2013 and June 2014. He said he was in Spain so often because of plans to base four U.S. naval destroyers there as part of the new anti-missile shield. Mabus was there when the first ship arrived in February, was the U.S. representative for a funeral there in March, then was back again in June.

But he has also traveled to a number of tiny islands like Kiribati, Sao Tome, Palau, Micronesia and Tonga, as well as landlocked countries where there is little Navy or Marine presence. Lined up along his Pentagon windows are six large glass jars filled with sand he's collected from World War II battlefields he's visited.

Mabus' trips also provide fodder for a series of photography books he has self-published. The books sell for up to $220 each, according to the website. But Mabus said he hasn't earned any money from the books since becoming secretary. He said many photographs were taken prior to his Pentagon job, while others were taken during his Navy travels. In a statement, his staff said the photography doesn't interfere with his official duties.