The phrase "a substantial escalation of" is correct and usable in written English.
It can be used when discussing an increase or intensification of a situation, issue, or conflict.
Example: "The report highlighted a substantial escalation of tensions between the two countries over trade disputes."
Alternatives: "a significant increase in" or "a considerable rise in".
Israeli military officials repeated their assertion that the use of the rocket marked a substantial escalation of the conflict that called for strong measures.
Junior doctors have already staged six walkouts this year as part of their campaign against the proposed new contract being imposed on them by the government, but Stephenson said the BMA was now planning "a substantial escalation" of the dispute.
The implicit threat of not only ratcheting up the drone strikes but also launching more covert American ground raids would mark a substantial escalation of the administration's counterterrorism campaign.
"A substantial escalation of the sovereign debt crisis would, of course, have an adverse impact on the German financial system, too," said Sabine Lautenschläger, a member of the Bundesbank's executive board who is responsible for bank regulation.
One supports a robust strategy of counter-insurgency, requiring a substantial escalation of troops that would bring the total number of U.S. forces to as many as 100,000.
Military authorities in Ukraine believe the number of Russian troops within and close to its borders has risen to more than 50,000, raising fears of a substantial escalation in the conflict raging in Ukraine's eastern regions.
Renal replacement therapy (RRT) is often required and represents a substantial escalation in the complexity and cost of care for critically ill patients with AKI [ 4].
But, more important, it represented a significant escalation of cyber warfare and demonstrated the quickly accelerating skills of hackers everywhere.
His Russian counterpart Sergei Lavrov said, quoted by the Russian Interfax news agency, that if heavy weapons were withdrawn "we'll be able to speak of a substantial de-escalation of the current conflict".
He defended the EU's "calibrated" approach to the situation in Ukraine from criticism it was being too soft on Russia, saying "far-reaching" economic sanctions would result in the event of a substantial further escalation.
