President Trump’s decision to replace Defense Secretary James Mattis on Jan. 1 – rather than allowing him to stay on the job until Feb. 28, as the retired Marine general requested when he resigned Thursday – was the right move.

Mattis no doubt thought a two-month transition would be helpful to his successor and minimize any disruption caused by his departure. But no president would want an avowed opponent of his foreign and national security policies to continue running the Pentagon for that long.

As Mattis correctly stated in his resignation letter to the president: “Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position.”

President Trump announced that Deputy Defense Secretary Patrick Shanahan, a former Boeing executive, will serve as acting secretary of defense. That’s understandable for the short-term to fill a sudden vacancy. But the president should choose a long-term replacement for Mattis who supports Trump policies priorities and who has more political and communications skills.

Mattis did a masterful job at accomplishing the urgent mission of defeating ISIS. Although remnants of jihadist group exist, its one-time caliphate is now just another bloody chapter in the history of radical Islamist depravity.

But while Mattis had the proven skills of a highly successful combat commander to battle our enemies abroad, his strength was not fighting for the president’s policies in the halls of Congress or in media appearances to influence public opinion.

With Democrats gaining control of the House of Representatives on Jan. 3, it will become far more important for President Trump to have a defense secretary who can be an effective advocate for presidential polices. The combination of Mattis’ limited advocacy skills and his opposition to many of the president’s policies requires that he be replaced quickly.

Despite his dedicated and outstanding service in the Marines, in his job heading the Defense Department Mattis was ill-suited to helping a president who ran for office on a promise to break from the foreign policies of Presidents George W. Bush and Barack Obama.

As a presidential candidate, Trump made clear that he wanted to end the failed nation-building gambits and prolonged wars in Afghanistan, Iraq and Syria that his predecessors pursued. As President Trump sought to implement a new path, Mattis resisted.

And Mattis had many other disagreements with Trump policies as well.

The defense secretary opposed the president’s decision to withdraw from the deeply flawed Iran nuclear deal. Mattis was against moving the U.S. embassy in Israel from Tel Avis to Jerusalem. He wanted to the U.S. to support the Paris climate agreement – a boondoggle that President Trump rightly opposed because it would have disadvantaged the U.S.

A president expects the opposing political party in Congress to fight against his priorities and initiatives. He doesn’t expect to have to battle members of his Cabinet. 

Mattis resisted sending U.S. troops to the Mexican border. He opposed strongly pressing NATO allies to spend what they pledged on their own defense.

Mattis also misspent the hard-won increases in defense spending that President Trump secured from Congress, devoting the money to wars in the greater Middle East rather than to buying new ships, planes and missiles. The defense secretary conducted fewer freedom-of-navigation exercises against the Chinese than his Obama-era predecessors.

A president expects the opposing political party in Congress to fight against his priorities and initiatives. He doesn’t expect to have to battle members of his Cabinet.

The next Pentagon chief needs to be both an advocate for President Trump’s vision of America’s military role in the word and a political pro who can install a pro-Trump network at the Defense Department.

Instead of a nominee who will go before the Senate and downplay the president’s decision to withdraw from Syria and the expected troop drawdown in Afghanistan, President Trump needs a defense secretary who will unabashedly remind Washington that the public wants an end to nation-building and wars that go on and on and on.

Our heroic American troops have been fighting in Afghanistan for over 17 years – slightly longer than earlier generations fought in World War I, World War II, Korea, Vietnam and the Persian Gulf War combined. U.S. forces have been fighting in Iraq for over 15 years.

Congress likes to bellyache about not being sufficiently consulted on war and foreign policy, so let’s have a debate. For example, President Trump’s nominee for defense secretary should remind senators that polls have recently shown that Americans want a troop drawdown in Afghanistan as opposed to build-up by a margin of two to one.

And the polls show that only 20 to 25 percent of Americans think we’re winning in Afghanistan. Furthermore, only 15 percent of Americans think we have a clear strategy in Afghanistan.

In addition to explaining what the Trump administration won’t do, Trump’s nominee for defense secretary should explain what the administration will do.

Withdrawing ground forces from Syria does not amount to abandoning the region. Rather, it can be a chance to return to America’s Reagan-era military posture in the Middle East, which centered around naval and air power, especially in the Persian Gulf.

This will be far cheaper than continuing the wars in Afghanistan, Iraq and Syria, which cost more than $60 billion per year. It would also mean building more military platforms that can be useful in a crisis with China or Russia – something that is not true with ground forces skilled primarily in counterinsurgency.

Indeed, the most important reason to draw down U.S. troops in the greater Middle East and Europe is to focus instead on deterring war with an increasingly belligerent and capable China.

President Obama boasted of a “pivot” to Asia and a “rebalancing,” but our real presence in the Pacific atrophied over the past decade as our Navy and Air Force shrank.

The current fiscal year’s defense budget of $717 billion is probably the high-water mark of military spending in the Trump administration. With a House run by Democrats, the only direction for military spending to go is down.

Putting more forces in the Pacific to deter war with China means making cuts elsewhere, not increasing the overall budget. We have to start making choices.

Finally, bringing on a new secretary of defense gives President Trump a chance to make a bold move in Europe. The president should turn our military bases in Europe over to our NATO allies and withdraw most U.S. troops.

We have kept troops in Europe since World War II, and that war ended 73 years ago. Our European bases have been obsolete since the collapse of the Soviet Union in 1991, and they’ve been of no use to us in the conflicts in Afghanistan, Iraq and Syria.

Why should U.S. troops defend Germany, for example, where polls show only 30 percent of Germans have a favorable view of America? On top of that, Germany treats us unfairly on trade,  fabricates anti-American news, and is rich enough to defend itself.

What’s the point of U.S. bases in Spain and Italy? Instead, we should pre-position heavy weaponry in pro-American Poland to deter Russia, because it would be cheaper than relying on NATO.

Finally, we should move more naval forces out of the Atlantic and into the Pacific.

These are the practical steps to further implement President Trump’s America First foreign policy. But all of them require a secretary of defense with vision and political skill. Mattis didn’t fit that bill, despite his skills on the battlefield.

President Trump should take the time to find someone who agrees with his campaign promises and agenda, and who can build support for his policies in Congress and with the public.

The American people elected Donald Trump to be our president because of the policies he advocated. The president needs a defense secretary and other Cabinet members who will help him implement those polices.