Russia has fine-tuned its hybrid-warfare strategy and has used it to project power and influence around the world, a major new Pentagon study says.

The study argues that the U.S. must develop a more robust, comprehensive strategy to counter Moscow’s 21st-century aggression.

Produced by scholars from the military and academia, the study was prepared for the Joint Chiefs of Staff. Politico first reported its contents over the weekend.

The study says that Russia continues to perfect its operations in the so-called gray zone — areas short of direct, all-out war that still have dramatic foreign policy and geopolitical impacts.

Examples include Russia’s efforts to influence foreign elections, its spread of disinformation, its deployment of paramilitary forces to hot spots around the world, its use of energy resources as a political weapon, and a host of other examples.

Fundamentally, the report says, Russia believes it is at war with the U.S. and is acting accordingly.

“Like Russia’s perception of its competition with the US, its perception of conflict is dichotomous: one is either at war or not at war,” the study reads. “To fight and win this war, Russia believes that the successful integration of all instruments of state power, as well as the orchestrated employment of non-military and military means to deter and compel, are paramount.”

“Overall, Russia’s influence abroad is growing, and the Kremlin has mastered the use of ‘hybrid warfare’ in driving Russia’s foreign policy,” the report continues.

The report’s release came as President Trump met with Russian President Vladimir Putin at this year’s G20 summit in Osaka, Japan.

Mr. Trump said he again confronted Mr. Putin about meddling in the 2016 U.S. election — a key example of Moscow’s efforts to exert influence around the world. The president said Mr. Putin denied allegations of election interference.

“How many times can you get someone to deny something?” Mr. Trump said. “We talked about it. We talked about a lot of other things.”

But the Pentagon study argues that election interference is just one example of Russia’s multi-pronged strategy to reclaim status as a major world power.

In Europe, for example, the report examines how Russia has used its energy resources — and the fact that Europe is increasingly dependent on Moscow for its energy needs — to wield political influence across the continent.

The strategy also includes its development of the Nord Stream 2 pipeline, a massive project that will deliver huge quantities of fuel directly to Europe.

Another example can be found in Venezuela, where Russia quickly gave a full-throated support to socialist President Nicolas Maduro as a way of thwarting American objectives. The Trump administration has demanded Mr. Maduro step down and instead recognizes political opposition leader Juan Guaido as the country’s rightful president.

The report’s overarching theme is that the U.S. needs a sweeping, comprehensive plan to fight back against Russia.

“Despite the strength of Russia’s growing influence abroad and the diverse array of gray zone tactics it uses to achieve its strategic goals, the US can still limit the results of this grand strategy,” the study says. “There is broad consensus among the contributors that countering Russian provocations will require the use of all instruments of national power.”