Outgoing U.S Secretary of Defense Chuck Hagel recently warned NATO of a potential growing divide within Europe between Northern and Southern countries within the group as the growing number of conflicts in Ukraine and the Middle East continue to be a test of the union’s strength.

“I am very concerned by the suggestion that this alliance can choose to focus only on one of these areas as our top priority”, secretary Hagel said at a press conference on Thursday in Brussels which may be his last major press outing as the acting secretary. Hagel is likely to be replaced by Ashton Carter whose final vote of confirmation by Congress could take place on Wednesday.

NATO is being challenged by numerous threats on its borders, as northern countries such as Poland, Slovakia, Hungary, and Belarus feel increasingly threatened by a resurgent Russia. Ukraine is today heart of that threat as the country continues to fight a civil war that started only in November 2014 when former President Viktor Yanukovich cancelled an economic agreement which would have moved the Ukraine closer to the EU, sparking protests throughout the country leading to Yanukovich’s eventual ouster.

In the most recent violence in Ukraine, 37 people were killed on Tuesday marking one of the single most deadliest days since the outbreak of the war, just ahead of another scheduled round of peace talks in Minsk attended by the United States, Russia, Ukraine and France.

“The shelling is with Vladimir Putin’s compliments who else could have done this?” A resident from Kramatorsk yelled as he walked by a shell that was unexploded.

Meanwhile, countries along NATO’s southern border such as Spain, Greece and Italy are being hit with a refugee crisis from Northern Africa and Syria as the nearly four-year-old Arab Spring-inspired revolutions continue to send refugees to Europe. Along with the potential for radical fighters from these conflicts returning to Europe, these nation’s long-term immigration concerns are threatening to consume their domestic politics just like the war in Ukraine is doing in Europe’s north.

“I worry about the potential for division between our Northern and Southern allies” Mr. Hagel continued in his remarks at the press conference on Thursday. “Hagel has been pushing back on the administration in regards to the defense budget and some of the defense policy and that’s kind of what led to this,” an aide for Mr. Hagel said in regards to the resignation.

Mr. Hagel resigned as Secretary of Defense on Monday, November 24th 2014, as he and President Obama are rumored to have developed major differences on key policy areas such as U.S. policy in Afghanistan.

“Chuck was frustrated with aspects of the administration’s national security policy and decision making process” Arizona Senator John McCain said regarding Hagel’s resignation. “Predecessors have spoken about the excessive micro-management from the White House and how that made it more difficult to do their jobs successfully. Chuck’s situation was no different,” Senator McCain went onto say.

Hagel’s warning also comes as threats of unrest in northern Africa continue to sporadically erupt especially in Libya where there has been unrest ever since the overthrow of Muammar Gaddafi in 2011 at the height of the popular Arab Spring uprisings. Rickety boats filled with refugees have since been pouring into southern Europe in increasing waves.

A new report that highlights the dangerous situation that the Middle East, specifically Syria and Iraq pose showing that over 20,000 foreign fighters have travelled to join armed insurgent groups like ISIL, who have claimed a significant amount of territory since 2014.

Ultimately, as Hagel rightly pointed out, NATO will have to remain focused on all regions at the same time despite the fact that there are many challenges ahead for the organization that will threaten organization’s focus on its mission of keeping the Western world safe from threats.