Updated

Six U.S. fighter jets have arrived in Estonia, as part of the United States' broader effort with NATO allies to support the Baltic Air Policing Mission as Russia continues to threaten invasion in Ukraine, United States European Command said Wednesday. 

The F-15E fighters belong to the 48th Fighter Wing of the U.S. Air Force and arrived to Estonia from their permanent home base in United Kingdom Lakenheath Air Force Base. EUCOM said the fighters would remain in the region until the end of next week. 

"Baltic and enhanced Air Policing are enduring NATO missions that deliver constant vigilance of Allied airspace and contribute to the Alliance’s collective defence posture," Major General Jöerg Lebert, Chief of Staff, Headquarters Allied Air Command said. "The additional aircraft will work closely with the current detachments to increase our readiness, build crucial interoperability and underline the robust solidarity across the Alliance." 

Six U.S. F-15E Strike Eagle fighters arrived at Ämari Air Base in Estonia, Wednesday, Jan. 26, 2022.

Six U.S. F-15E Strike Eagle fighters arrived at Ämari Air Base in Estonia, Wednesday, Jan. 26, 2022. (U.S. Air Force photo by Staff Sgt. Megan Beatty)

The exercises are expected to increase the level of cooperation of NATO Allies in responding to potential crises around the world.

STATE DEPARTMENT ISSUES ‘DO NOT TRAVEL’ WARNING FOR UKRAINE AS EMBASSY STAFF IS TOLD TO LEAVE

According to the decision of the North Atlantic Council, the air forces of NATO member states have been guarding the airspace of Estonia, Latvia and Lithuania since 29 March 2004, when the Baltic States became members of NATO. As part of the 2012 Chicago Summit, the North Atlantic Council extended the Baltic Air Security Mission indefinitely, EUCOM said. 

The arrival of jets comes as President Biden is weighing whether to deploy thousands of U.S. troops to Eastern Europe to bolster a broader NATO effort to protect allied countries bordering Russia and Ukraine. 

Defense Secretary Lloyd Austin, on Monday, put 8,500 U.S. troops on heightened preparedness in case of a decision to deploy. 

Airmen from the 4th Fighter Wing at Seymour Johnson Air Force Base, N.C. and the 48th Fighter Wing, Royal Air Force Lakenheath, England, arrive at Ämari Air Base, Estonia, Jan. 24, 2022. 

Airmen from the 4th Fighter Wing at Seymour Johnson Air Force Base, N.C. and the 48th Fighter Wing, Royal Air Force Lakenheath, England, arrive at Ämari Air Base, Estonia, Jan. 24, 2022.  (U.S. Air Force Photo by Staff Sgt. Megan Beatty)

The troop deployment would be part of a broader NATO effort. Other NATO countries may also contribute troops to warn Russian President Vladimir Putin not to try to move into neighboring countries.

NATO SENDING FIGHTERS, SHIPS TO REGION; UK TO WITHDRAW SOME STAFF FROM EMBASSY IN UKRAINE

As part of the effort, Biden is also considering deploying naval vessels for NATO allies who may feel threatened. Some equipment and troops in these proposed actions would come from Europe and some would come from the U.S.

NATO said that it is "sending additional ships and fighter jets" to Eastern Europe. This includes F-16s from Denmark, naval forces from Spain, and F-35s from The Netherlands. France is ready to send troops to Romania, which borders Ukraine to the south. 

As Biden weighs deploying troop, the State Department ordered the evacuation of American citizens in Ukraine on Sunday. Officials also ordered family members of employees at the United States Embassy in Kyiv to leave the country. 

That announcement came after the U.K.'s Foreign, Commonwealth & Development Office announced on Saturday that it had information suggesting that the Russian government is plotting to install a pro-Kremlin leader in Kyiv.

Ukraine's territory has long been in Putin's crosshairs, especially amid recent NATO considerations of potentially allowing Ukraine to join the alliance. It is one of several post-Soviet republics in the region that shifted toward an alliance with the West after the collapse of the Soviet Union. 

Putin was in the Soviet KGB for many years before beginning his political career, and has said the collapse of the Soviet Union was the "greatest geopolitical catastrophe" of the 20th century. 

RUSSIA AND UKRAINE: BIDEN AND NATIONAL SECURITY TEAM DISCUSS POSSIBLE US TROOP DEPLOYMENT TO EASTERN EUROPE

Putin also stresses Russian ethnic and cultural influences in Ukraine as reasons why it should be part of Russia. That was a significant part of the justification Russia used when it illegally annexed the Crimea region of Ukraine in 2014. 

Six F-15E Strike Eagles, assigned to the 4th Fighter Wing from Seymour Johnson Air Force Base in N.C., receive routine maintenance after arriving at Ämari Air Base, Estonia, Jan. 26, 2022. 

Six F-15E Strike Eagles, assigned to the 4th Fighter Wing from Seymour Johnson Air Force Base in N.C., receive routine maintenance after arriving at Ämari Air Base, Estonia, Jan. 26, 2022.  (U.S. Air Force Photo by Staff Sgt. Megan Beatty)

While NATO and the United States are fortifying allies, including the Baltics, it is not likely the western alliance will send troops into Ukraine itself, where they would be at risk of a potentially major military engagement with Russia. 

CLICK HERE TO GET THE FOX NEWS APP

Biden administration officials told Fox News on Tuesday that they are also preparing "severe" sanctions against Russia should they invade Ukraine, which would have an "immediate and visible effect on the day they are implemented." 

"That means the gradualism of the past is out, and this time, we will start at the top of the escalation ladder and stay there," a senior administration official said. "We've made efforts to signal this intention very clearly, and I would say, a deepening selloff in Russian markets, its borrowing costs, the value of its currency market, imply default risk, reflect the severity of the economy consequences we can and will impose on the Russian economy in the event of a further invasion."