Article 4 would start collective discussions amongst the alliance. Reinsalu called for like-minded countries to invoke the clause together and "without delay". He made the proposal to Prime Minister Kaja Kallas (Reform) via social media.

"We should present our proposals to the allies to improve the security situation. First, increasing the allied military presence in the Baltic-Polish space, secondly, the revision of Baltic-Polish defense plans and, thirdly, NATO must explicitly and completely reject the draft agreement presented in the form of a Russian ultimatum," the MP said.

"Our vital security interests are more threatened now than ever after our accession to NATO, and we need to state this loudly and with clear arguments."

Reinsalu said this is not the time to act passively: "This is not an ordinary diplomatic conflict situation between countries, but from a neighboring country with nuclear weapons, which ultimately threatens to use military force if NATO is not essentially dismantled in Eastern Europe."

He called for new sanctions to be imposed on Russia to discourage large-scale military activities in Ukraine.

Last month, Russia issued a series of demands to the U.S. that NATO should roll back its presence on its Eastern flank and, including in the Baltics, and rule out Georgia or Ukraine joining the alliance in the future.

Estonia's ambassador to NATO Jüri Luik (Isamaa), at the time, said NATO is calmly dealing with Russia's demands and the country has further damaged its "already very bad" reputation with its recent actions.

What is NATO's Article 4?

Article 4 of NATO's founding treaty says:

"The Parties will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened."

Any member country can formally invoke Article 4. As soon as it is invoked, the issue is discussed and can potentially lead to some form of joint decision or action on behalf of the alliance.

Whatever the scenario, fellow members sitting around the Council table are encouraged to react to a situation brought to their attention by a member country.

Since the Alliance's creation in 1949, Article 4 has been invoked six times. 

--

Follow ERR News on Facebook and Twitter and never miss an update!