The phrase "diplomatic situation" is correct and usable in written English.
You can use it when referring to a problem or issue that needs to be handled with a diplomatic approach rather than a confrontational one. For example, "The diplomatic situation in the Middle East is delicate and needs to be handled carefully."
Flynn lied to the F.B.I., too, about asking the Russian Ambassador not to escalate the diplomatic situation between the U.S. and Russia after the U.S. expelled Russian diplomats following the revelation that Russia meddled in the election.
The diplomatic situation remained unclear.
The diplomatic situation was volatile; negotiating loans proved impossible.
"Sharon has a very severe diplomatic situation," Mr. Peres said.
"We're not in a military situation; we're in a diplomatic situation," the colonel said.
Moscow's decision to postpone Putin's visit has saved the Élysée from a potentially difficult diplomatic situation.
Drawing on her own wide experience in social, political, and diplomatic situations, no less a personage than Eleanor Roosevelt published her own typically practical Book of Common Sense Etiquette (1962).
As Bobo Lo, of the Royal Institute of International Affairs in London, puts it, Russia has a taste for "controlled tension": diplomatic situations short of conflict, in which Russia's membership of the UN Security Council gives it extra clout, as in the run-up to the Iraq war.
However, in yet another 1958 case (Perez v. Brownell), the Supreme Court affirmed the provision revoking the citizenship of any American who had voted in an election in a foreign country, as a legitimate exercise (under the Constitution's Necessary and Proper Clause) of Congress' authority to regulate foreign affairs and avoid potentially embarrassing diplomatic situations.
In terms of upstaging, this is a diplomatic neutrality situation.
New season notwithstanding, the sport is still stinging from the multiplicity of last spring's -- let's be diplomatic -- situations.
