NATO’s secretary-general Jens Stoltenberg is shouting the alarm over Russia’s recent buildup of military forces from the Mediterranean to the Baltic Sea and is wanting the U.S.-led alliance to respond.

Stoltenberg addressed the issue at a news conference in Portugal during NATO war games. He stated that he is worried that Russia’s military could limit access to those regions for the United States and its allies, according to Fox News.

“We have to be sure that we are able to overcome these capabilities, so we can reinforce, so we can move and we can deploy forces if needed,” said Stoltenberg.

Leaders and representatives of nine Eastern European NATO member nations met on Wednesday. Due to Russia’s annexation of Crimea from Ukraine and threats from ISIS, NATO leaders called for an increased alliance presence in Europe.

In the past, NATO has refrained from deploying permanent substantial combat forces due to an agreement with Russia that dates back to 1997. However, this year NATO has been deploying small military units in and out of countries that they feel is at risk from Russia. NATO has been careful not to make it appear to the Kremlin as if they are deploying permanent reinforcements, according to the Associated Press. Although, Stoltenberg’s comments hint that NATO might be rethinking this agreement.

Meanwhile, Russia continues to build upon their current military presence in Syria. CBS News reports that Russia has recently brought in anti-aircraft missiles to Syria to protect their jets from being attacked or hijacked. Russian military officials did not specify how many missiles or what type of missiles were brought into Syria.