U.S. Strategic Command head Gen. John Hyten said the U.S. had "no defense" for Russia's SSC-8 nuclear-capable cruise missiles in Europe.
Russia fired missiles only miles away from NATO forces in the volatile Black Sea region, where the U.S. has accused Moscow of threatening its interests.
NATO has planned to spend over $3.2 billion on a large boost to the 28-member military alliance's electronic and satellite communication defense systems.
Moscow's attempts to regain influence in the Balkans shows the perils of backing off Russia.
Tillerson's potential no-show had increased unease caused by U.S. President Donald Trump's description of NATO as "obsolete" during his election campaign.
Tillerson argued that Montenegro's membership in the alliance would support greater integration, democratic reform, trade, security and stability among its neighbors.
A day after meeting Angela Merkel, Trump tweets the 'United States must be paid more for the powerful, and very expensive, defense it provides to Germany.'
Diplomats from Ukraine and five other former Communist countries rallied for the U.S. Senate’s backing.
The call was the first that Moscow accepted, according to NATO.
Objections by Republican Senators Rand Paul and Mike Lee have blocked a vote in the full Senate.
Ukraine’s fleet is looking for minesweepers and coast guard ships for the Black Sea.
In doing so, Trump also insisted that friends and partners from Europe to the Middle East to the Pacific must “pay their fair share of the cost.”
Vice president seemingly contradicts Trump at Munich conference, as the president has been critical of the alliance.
Trump's contradictory remarks on NATO, calling it "obsolete" during the U.S. election campaign but also supporting it, as well as his praise for Russian President Vladimir Putin, have deeply unsettled allies who fear for transatlantic ties.
Jens Stoltenberg announced 3.8 percent of spike in real terms across Europe and Canada.
NATO and EU officials are increasingly worried about Russia's ability to spread disinformation via TV and internet.