Expelling "diplomats" is perfectly lawful. But seizing diplomatic property is a clear and dangerous breach of the Vienna Convention. I know all about this as I had to study whether the UK could legally seize Ecuador's embassy. No--even if every diplomat is expelled.
The Vienna Convention governs all diplomatically certified buildings. Inviolability is explicit. Obama's seizure of two Russian embassy properties is seen by the global diplomatic community as beyond the pale. Why? Not because of any great love of Russia. But because it places all embassies everywhere at risk by setting a new norm. That is why even countries that opposed the US supported its rights in relation to the 1979 occupation of its embassy in Tehran.
Obama's action in seizing the two Russian embassy properties is much worse than the seizure of the US embassy in Iran. Why? Because...Iran had just had a revolution and was in chaos. Protestors and not the Iranian government occupied the embassy (at least formally). By contrast, the US seizure of Russia's property was proclaimed to be an act of state, a flagrant and destabilizing breach of Vienna.
The Vienna Convention on Diplomatic Relations is not just some obscure international law. It is the foundation of all diplomatic law. It is the most widely obeyed and respected international law there is. It governs every diplomat, embassy and consulate.
So Obama's flagrant breach of it strikes at the heart of the entire diplomatic system. Normally it is only seen when armed mobs take over and a militia occupies an embassy. As both the US and Russia are signatories to the Optional Protocol on Disputes, any time Russia wants to it can take the case to the International Court of Justice and win within months. https://www.state.gov/documents/organization/17843.pdf
If the US doesn't obey the ICJ ruling on it, it will alienate the global diplomatic community and the ICJ. It will then be open season on US diplomats and diplomatic properties around the world and states will look to take other ICJ cases against the US since its standing at the ICJ will have diminished, increasing the chance of victory for the plaintiff.
[This] is likely why we are seeing talk about the US giving the Russian properties back. The Trump admin doesn't want to look weak or frightened or as if it can be pushed around by the ICJ or the global diplomatic community, so it pretends that its a quid pro-quo for Russia playing nice in Syria.
~ Julian P. Assange, Ecuadorian Embassy, London , July 14, 2017
10 million documents
10 billion words
Re: The 1961 Vienna Convention on Diplomatic Relations (VCDR) and the 1963 Vienna Convention on Consular Relations form the core of international diplomatic and consular law.
Some of the Whistleblowers
and their Intermediaries
The G.E. Three
Gregory C. Minor
Richard B. Hubbard
Dale G. Bridenbaugh
Glenn Edward Greenwald
Konstantine von Motz
and many more...