Sen. Bernie Sanders' foreign policy leaves much to be desired.

The US needs to recover its standing in the world once President Trump leaves office, but Sanders' plans wouldn't help with that goal.

Brett Bruen was the director of global engagement in the Obama White House and a career American diplomat. He runs the crisis-communications agency Global Situation Room.

This is an opinion column. The thoughts expressed are those of the author.

Visit Business Insider's homepage for more stories.

Bernie Sanders has a big problem: his weak foreign policy plans.

The senator from Vermont has mostly tried to skate past substantive discussions on national security, falling back instead on a few shallow canned comments. As one of two serious candidates left in the Democratic primary, this lack of foreign policy focus is alarming and unacceptable.

His revolution has mostly revolved around economic grievances and transformation. I remember 25 years ago as Page in the US House of Representatives listening to then-Rep. Sanders go on and on about economic insecurity, but hardly ever national security

Listening to Bernie now, it's easy to forget that the President's first priority isn't the economy. His or her most important responsibility is protecting our country as Commander in Chief. That ought to be the issue that weighs most heavily and most often on voters' minds. His justification for staying in the race is largely based on the belief he can bring Joe Biden closer to his policy positions and spending more time on his issues. So it's safe to assume that leads to a lot less discussion of national security.

We should not allow, as we did with Donald Trump, presidential candidates to get away with delivering catchy one liners on national security. This is serious stuff. We have certainly seen over the last three years, especially with the current slapdash handling of the coronavirus, the cost of a president who is unable to effectively manage a global crisis.

Sanders' scant details

Just look at Sanders' website. It offers scant details of his plans and proposals for foreign policy. There are several mentions of ending USs militarism, whatever that means. There are few mentions of specific countries, apart from an obvious commitment to rejoin the Iran Deal with our allies and ending Saudi Arabia's attacks on Yemen.

The worst line is actually the last one. He writes that, "in the United States, Europe, and elsewhere, democracy is under threat by forces of intolerance, corruption, and authoritarianism." Since when do we say Europe and elsewhere? There are clearly threats in Asia, Latin America, and the Middle East that shouldn't be painted with a broad brush by a man who wants to be president. It's amateurish.

Then come the controversial comments about Venezuela, Bolivia, and Cuba. Sanders has long staked out a position against mainstream American policies towards the region. While claiming to put human rights at the core of his global engagement, he seems to have no problem looking past the brutal abuses of fundamental freedoms in those countries.

So, what does he really mean and what would he do as president? My assessment at this point is that we would unfortunately see a continuation of the isolationist tendencies that have become the hallmarks of Trump's foreign policy. Indeed, Sanders regularly seems to confuse American intervention with standing up for our ideals and those in danger.

A Sanders Administration would tell us that the days of militarism are over. But while war may not be the answer, the question then becomes: what's your plan instead? Sadly, Sanders doesn't seem to have a great solution.

Some will say that if the United States simply engaged in fewer foreign interventions this would greatly diminish the danger. But the US still needs a plan to confront authoritarian leaders or they will become bolder and brasher.

There was a dearth of details during Sanders' interview with NPR's Rachel Martin. She pressed him repeatedly on how he would tackle extremism in Iraq and elsewhere. He talked about past problems. He raised Trump's recklessness. He mentioned the importance of diplomacy. The reporter clearly wanted a more substantive response. A frustrated Sanders finally said, well America has a lot of money and that can be used to solve foreign crises.

There is an argument to be made that foreign aid might increase under Sanders. But, I'm not convinced he could actually get Congress to pour substantial sums into the aid budget. Sanders has an ambitious domestic agenda and there's good reason to believe that will be the fiscal priority, not foreign aid.

Those voting in the Democratic primary should be concerned by Sander's treatment of foreign policy. The world and our standing in it after Trump will be incredibly complex and challenging.

Holding up protests and votes against war that happened decades ago is not a solution to today's conflicts. Throwing money at adversaries or disengaging militarily won't end wars. If he wants us to take him more seriously, then Bernie needs to take a much longer, harder look at our national security and come up with some serious plans.