The end of the week brought more assurances from NATO and key individual allies. US President Barack Obama participated in a conference call with Estonian President Toomas Hendrik Ilves, Latvian President Andris Bērziņš and Lithuanian President Dalia Grybauskaitė on Saturday to assure them of NATO's highest consideration.
"The President reaffirmed the United States' unwavering commitment to our collective defense commitments under the North Atlantic Treaty and our enduring support for the security and democracy of our Baltic allies," the statement said. "The Baltic leaders welcomed the provision of additional support to NATO's Baltic Air Policing mission, and the leaders agreed to continue coordinating their efforts closely."
The weekend also saw other conference calls between Obama and world leaders, which reiterated calls for Russia to pull its military forces back to their bases, allow for the deployment of international observers and human rights monitors to the Crimean peninsula, and agree quickly on the formation of a contact group that could lead to direct dialogue between Ukraine and Russia to de-escalate the situation and restore Ukraine's sovereignty and territorial integrity.
The leaders rejected the proposed referendum in Crimea as a violation of Ukraine's constitution, and underscored that all decisions about the future of Ukraine must include the government in Kiev.
Late on Friday evening Estonian time, US Joint Chiefs Chairman Gen. Martin Dempsey made one of the strongest comments indicating that the NATO tripwire was deployed. While the US would play it by ear in Ukraine itself, he told PBS the "message" being sent was to NATO allies. "Remember, we do have treaty obligations with our NATO allies. And I have assured them that if that treaty obligation is triggered, we would respond."
NATO added six F-15s and air-to-air refueling capability to the Baltic State Air Policing mission last week. The fighters are based out of Zokniai air base, once the home of Red Army troops, 7 kilometers southeast of the northern town of Šiauliai. The fighters are in addition to the four American F-15s that were already deployed there as part of the regular NATO rotation.