As President Trump deals with multiple security crises around the world, his foreign policy doctrine is coming into sharper focus – with an emphasis on projecting American military strength overseas.

To that end, the president has reversed a major campaign promise on America’s involvement in NATO, saying earlier this week the alliance is no longer obsolete.

“The secretary general and I had a productive discussion about what more NATO can do in the fight against terrorism,” President Trump said.

The U.S. military is now focusing on rebuilding its forces in eastern Europe, as a deterrent to potential enemies like Russia and Iran.

On Thursday, some 900 U.S. soldiers took up position in Poland – the first deployment of a multi-national force being posted across the region.

“Now deploying you, deploying these troops to Poland is a clear demonstration of NATO’s unity and resolve and sends a clear message to any potential aggressor,” Gen. Curtis Scaparrotti said.

But pivoting back to Europe won’t be easy after decades of focusing on emerging threats from East Asia and the Mideast.

Officials there are now urging the U.S. to continue supporting European security which, they say, also plays a role in keeping America safe.

“It is in the U.S. interest to have a European Union able to assume its defense capacity in addition to NATO, and a European Union that plays its political role,” Jean-Marc Ayrault, France’s foreign minister, said.

In addition to the troop deployments, the Pentagon is sending a squad of F-35 fighter jets to Europe this weekend as part of what it calls the “European Reassurance Initiative.”