What did the Kerch Strait clash change by 27 November 2018?

What had the Kerch Strait confrontation set in motion by 27 November 2018? Two days after Russian forces fired on and seized three Ukrainian Navy vessels, its consequences were reaching well beyond the strait itself.

The incident began on 25 November 2018. As reported at the time, Russia blocked the passage of three Ukrainian vessels under the Kerch Strait Bridge by placing a cargo ship in the way. Russia said the vessels had violated its territorial waters and ignored warnings. Ukraine denied that its ships had done anything wrong. Shots were fired and the vessels were seized. Ukraine reported 23 sailors taken prisoner, six of them wounded; Russia said three Ukrainians were wounded. Ukrainian accounts also said a Russian border patrol ship rammed the tug Yani Kapu while the group was moving from Odesa to Mariupol.

Kyiv responded quickly. On 25 November an emergency meeting of the National Security and Defense Council was convened, after which President Petro Poroshenko said he would ask the Verkhovna Rada to back martial law. On 26 November the parliament approved martial law in 10 oblasts for 30 days, starting on 28 November 2018. The same day, Russia asked for an urgent meeting of the UN Security Council, and the Kerch Strait was reopened to commercial shipping.

A summit in doubt

On 27 November 2018 the diplomatic fallout reached Washington. U.S. President Donald Trump said he might cancel his planned meeting with Russian President Vladimir Putin at the G20 summit in Buenos Aires later that week, citing the maritime clash with Ukraine.

Later accounts describe the incident as the first time Russian forces had openly engaged Ukrainian forces in the Russo-Ukrainian War. That was not yet a settled judgement on 27 November 2018, when the immediate questions were the fate of the captured sailors, the start of martial law the following day and whether the G20 meeting would go ahead.